What is the best exercise for fat loss? Part V – the conclusion

I wondered what the best exercise for fat loss was. I honestly didn’t know the answer, but now feel I have acquired a more thorough understanding. As a scientist I ask questions I want answered and work to find the answers. However, all this digging in the details and nerding about does not mean fat loss should be a primary motivation for exercising. On the contrary, if the only reason that you exercise is to try to lose weight and everything else about exercising is a pain in the ass, I would recommend you to stop exercising. No matter your external motivation for exercising, be it health in general, weight loss, muscle strength or flexibility, if you want exercise to be a positive part of your life you need to find an exercise form that gives you something more, that is motivated by internal factors, preferably that you enjoy the actual exercising. If you want to lose weight and you know high intensity strength based exercise is the most effective exercise, but you would rather swim because you really like swimming, than the choice is simple. Swim!

That being said, for the sake of curiosity, let’s see what the best exercise for fat loss is.

There is not enough data to say much about what exercise form is more efficient, whether running is better than cycling for example or a step machine better than elliptical trainer. There are just too many other variables. There is however enough data to make a calculated guess about aerobic versus resistance exercise, and about exercise amount and intensity.

Just wanted to illustrate the expected effects of exercising without dieting. The below table gives a few examples of just how much weight and fat you can expect to lose. Results are not god, and tend to become poorer in time in the longer lasting trials. Many of the results are non significant. What this tells us is that diet matters. A lot. 

It seems that resistance exercise is or can be just as effective as aerobic exercise in improving body composition. Resistance exercise usually cause some fat loss while also increasing muscle mass. Aerobic exercise usually causes larger loss of fat, but also larger loss of muscle. High intensity aerobic exercise causes less lean mass loss than low intensity.

The best exercise for fat loss should:

– be of medium to high intensity (frequently bring you above lactate threshold)

– include resistance exercises

– be interval based (30 min of sprint intervals is most likely better than 60 min jogging)

– not be performed every day (rest is important and more is not better than the right amount)

– exercise the whole body

– be combined with a high protein low glycemic diet for maximal improvement in body composition.

That’s it, as far as I can tell. Feel free to disagree. Tomorrow I’m off to the Norwegian Directorate of Health and the unveiling of the new national dietary guidelines. The snack there is crap (usually fruit), but hopefully there’s coffee and plenty of it.

What is the best exercise for fat loss? Part IV

The bias
I have this theory. In the last post I concluded that there is sufficient data for recommending high intensity exercise in favor of low intensity for fat loss. Admittedly, the data in support of this is not strong. It is there, but I would not bet my life on it yet.

I might be a bit biased in favor of high intensity because of my theory that seems rigidly stuck in my brain. From the world of resistance exercise, we know that you can use a number of strategies to build muscles. Some use slow movements with relatively low resistance where the muscles are activated for a long time. Others use quick movements with high loads allowing for a greater workload to be performed in a shorter amount of time. Some simply cut blood flow to the working muscles which also will make them grow. The bottom line is that the one important factor when it comes to muscle hypertrophy seems to be the amount of physiologic stress placed on the working muscles during exercise. So you can stress a muscle or muscle group by making it work for a long time like in static strength training or you can do the standard high load high repetition fast movement exercise. You can even do pure eccentric exercises rather than the usual concentric/eccentric. All of this and pretty much everything in between will cause muscle growth. It is the total workload, the time multiplied by load, that matters.

The concept is very similar to the energy hypothesis that claims it is the amount of energy spent during exercise that determines fat loss, rather than intensity or time by itself. The difference is that the hypertrophy theory is supported by science whereas the energy hypothesis is not.

Although hypertrophy can be achieved in many ways, there is a limit to the equation, workload = time x load. It is not only the amount of work done that determines muscle growth. Running, for example will not build significant amounts of muscle even if some of the muscles involved perform a great workload. The reason is that somewhere in the area between multiple repetition resistance exercise and endurance exercise the stimulus changes and thus the physiological adaptations.

Most people are aware of this and know that walking or running is a poor strategy for building muscles.

My theory is that the whole «exercise intensity and fat loss» issue is of a similar nature, that to a certain degree, it is the amount of work performed that matters the most. Both low and high intensity exercise cause fat loss, but somewhere in the declining intensity area the stimulus becomes different and fat loss is reduced. Shopping, gardening and other everyday activities with low intensity, but often of long duration seem poor strategies for weight loss. Likely, we are working to close to the body’s comfort zone to make it adapt. Or put in better words, the body does not adapt to these activities because it doesn’t need to, it already has.

This means that high or low intensity might not matter that much, as long as the tissues are exposed to new stimuli, forcing them to adapt. However, this is not to say that high intensity is not better than low, the question is how much better.

As with muscle hypertrophy, if the goal is to maximize all factors, then high intensity, high workloads and variation in stimuli is important. I believe it is the same with exercise intensity and fat loss. This might explain some of the variation in results found in different trials.

The losing of fat and not muscles
Loss of muscle mass is common with weight loss, independent of dietary approach. Some diets seem to lead to better muscle mass retention and some exercise forms will prevent muscle loss. But we must make sure not to assume that all muscle loss is a negative thing. The size of our muscles will determine our appearances while their function is what will affect our health.

In school I was taught that one important factor for skeletal muscle hypertrophy was positive energy balance. You had to take in more than you expended. This however, turned out to be wrong. The muscles might need a readily supply of fuel, but they couldn’t care less if the energy comes from glycogen and fat stores or from food. Thus it is theoretically possible to lose fat mass while increasing muscle mass.

Fleck and Kraemer [1] concludes that in untrained individuals doing regular resistance exercise you can expect a 2kg increased muscle mass in 14 weeks. That’s about 0.06kg per exercise session. If we consider the women only trials the number is about 0.04kg per session.

Resistance exercise builds muscles when we’re not dieting, but does this hold true when we are simultaneously losing fat mass? Short answer, yes. We can. But, you would not come to that conclusion if you put together a meta-analysis of decent trials. The reason is that in several studies fat loss is significant while muscle growth is not. However, when the mean is zero change, the individual data will show that many did increase their lean mass while losing fat.

I know this is a statistical quagmire, but part of my conclusion will still be based on individual results rather than the reported means. The reason is that when several people in a resistance exercise study build muscle, it is very likely that the exercise is to blame. This is not a strategy I would use when for example looking at weight loss results from low fat diet studies that show a mean zero improvement. If finding that half the participant lost weight and the other half did not, it would not be smart to claim that low fat diets works. There are a great many things that lead us to lose weight, although it almost always involves some reduction in dietary carbs. But as I said, when people gain muscle in a resistance exercise trial, the gain is extremely likely to come from the resistance exercise.

There is another issue as well. Many body composition studies are done with DEXA (dual energy x-ray absorptiometry). Because adipose tissue mass is considered 85% lipid and 15% water, and because DEXA measurement of fat free mass includes this adipose tissue water, a loss of adipose tissue without loss of fat free mass suggests favorable changes in muscle mass.

When I did a small study in 2009 I found that in eight women who did regular resistance exercise in combination with a ketogenic diet, four of them increased lean body mass, while four reduced it. The study was not large enough to indicate what factors were responsible for the lack of muscle mass gain in the other four. I guess anything from dietary protein (amino acids), thyroid issues to stress might contribute [2]. 

Figure 2 from Jabekk et al 2009. Lc+Ex= Low carb + resistance exercise. Ex=resistance exercise.
Shadid and Jensen [3] compared 20 weeks of pioglitazone with exercise and diet. Diet and exercise resulted in 11.8kg mean weight loss. The group was instructed in a 500kcal deficit diet and in an exercise program starting with 15min of aerobic exercise three times per week at 50% of each individual’s heart rate reserve. This was gradually increased to 45min aerobic exercise four times a week at 60–70% of heart rate reserve. The surprising find in the study was that the intervention caused a mean 9.5kg fat loss and a non significant 0.5kg reduction in fat free mass, which is an unusually small reduction.

Barbara A. Gower et al [4] also got surprisingly good results from a traditional very low energy diet in overweight women. Mean fat mass lost was 11.2kg. White women in the trial lost a non significant 0,77kg lean mass while the African American women lost 1.53kg (non significant) lean mass.

In both the above trials, several individuals managed to increase their lean mass while reducing fat mass. This was even done without any reported resistance exercise. Most if not all of the participants in the trials were insulin resistant, which if improved, I suspect can cause muscle growth by itself.

Gary Hunter [5] who coauthored the Gower trial found that in women who lost 12kg of weight, resistance exercise conserved lean mass. The women were randomized to diet only, diet and resistance exercise or diet and aerobic exercise.

Figure 1 from Hunter et al 2008. FFM=fat free mass. AA=african-american. EA=european-american
In a study from 1988 Douglas L. Ballor et al [6] concluded similarly to Hunter and stated that “In conclusion, data from this study indicate that weight training added to a caloric restriction program results in maintenance of LBW [Lean Body Weight] and regional increases in muscle area. When diet plus weight-training exercise is compared with exercise without caloric restriction, there is no difference in the rate of strength gain or magnitude of upper-arm muscle area increase.» 
From Ballor et al 1988. C=control. DO=diet only. DPE=diet plus exercise. EO=Exercise only. 
It might seem counterintuitive, but finding that endurance exercise increases lean mass or attenuate lean mass loss is quite common. Janssen et al [7] found that aerobic and resistance exercise did equally well in preserving muscle mass with dieting in premenopausal obese women. This finding reflected their previous (1999) trial with both men and women, which also found preservation of lean mass with both resistance and aerobic exercise.

Contrary to Janssen et al, Geliebter et al [8] and Bryner et al [9] did find that resistance exercise was more effective in improving lean mass with weight loss than aerobic exercise.

The combination of resistance training with aerobic training has been shown to be superior for body weight and fat loss and to result in greater lean body mass compared to aerobic exercise alone in several randomized controlled trials.

Park et al [10] for example, found that aerobic exercise reduced fat percentage by 9.2 while combining it with resistance exercise reduced fat percentage by 10.3. Lean mass increased by 0.9kg with aerobic exercise and by 5.6kg with combined exercise. This trial did not use a dietary intervention and the subjects had a mean BMI of 25. But it is an interesting example of how the exercise did not cause a weight change but still caused a significant body composition change.

Using a combination of high protein diet and resistance exercise Wycherley et al [11] demonstrated an 11.4kg fat mass reduction in 16 weeks. The reduction was accompanied by a 2.4kg reduction in fat free mass. The body composition results are impressive, but as I said we rarely if ever find a significant mean fat loss in combination with significant mean fat free mass gain.

Saving the best for last, Kevin David Ballard and colleagues is responsible for a meeting abstract from 2008 titled “Effects of diets restricted in fat and carbohydrate with and without resistance training on body composition and cardiovascular risk.” Ballard reports results from the Department of Kinesiology at University of Connecticut were heavyweights like Jeff Volek and William Kraemer reside. They report having examined the effects of carbohydrate restricted (CRD) and low fat diets (LFD) alone and in combination with resistance training (RT) in 47 overweight men.

The results state that “Reductions in body mass, fat mass, percent body fat and abdominal fat were greater in the CRD than the LFD (p<0.001).” and that “Gains in lean body mass were demonstrated in the RT groups only (p=0.004).” Their conclusion: “Resistance exercise is an effective strategy to combat diet induced losses of lean body mass.

On the matter of resistance exercise and fat-free mass Donnely and ACSM [12] concludes thusly: “…most studies combining resistance training with energy restriction report improved lean body mass compared to dieting alone.” They continue; “In summary, resistance training does not seem to be effective for weight reduction in the order of 3% of initial weight and does not add to weight loss when combined with diet restriction. Resistance training increases fat-free mass when used alone or in combination with weight loss from diet restriction. Resistance training may increase loss of fat mass when combined with aerobic exercise compared to resistance training alone.

Petra Stiegler and Adam Cunliffe [13] did a very good job addressing the evidence for the effect of exercise and diet on anthropometric variables. They conclude that: “…it becomes clear that a combination of modest caloric restriction combined with endurance exercise or endurance and physical training of different modes is preferable over dietary modification alone to induce favorable changes in body composition accompany ing weight loss.

The Conclusion 
It is possible to increase lean mass while losing fat mass. There are many factors at play but a high animal protein diet and resistance exercise is the best strategy we know of. Resistance exercise is very effective at increasing lean body mass, and it seems that this effect remains even if people are dieting and the effect is observed in both low and high carbohydrate diets. The addition of endurance exercise to diet and resistance exercise seems to slightly increase fat mass loss, but has little effect on lean mass.

The references

1. Fleck SJ, Kraemer WJ: Designing resistance training programs. Champaign, IL: Human Kinetics; 2004.

2. Jabekk PT, Moe IA, Meen HD, Tomten SE, Hostmark AT: Resistance training in overweight women on a ketogenic diet conserved lean body mass while reducing body fat. Nutr Metab (Lond) 2010, 7: 17.

3. Shadid S, Jensen MD: Effects of pioglitazone versus diet and exercise on metabolic health and fat distribution in upper body obesity. Diabetes Care 2003, 26: 3148-3152.

4. Gower BA, Weinsier RL, Jordan JM, Hunter GR, Desmond R: Effects of weight loss on changes in insulin sensitivity and lipid concentrations in premenopausal African American and white women. Am J Clin Nutr 2002, 76: 923-927.

5. Hunter GR, Byrne NM, Sirikul B, Fernandez JR, Zuckerman PA, Darnell BE, Gower BA: Resistance training conserves fat-free mass and resting energy expenditure following weight loss. Obesity (Silver Spring) 2008, 16: 1045-1051.

6. Ballor DL, Katch VL, Becque MD, Marks CR: Resistance weight training during caloric restriction enhances lean body weight maintenance. Am J Clin Nutr 1988, 47: 19-25.

7. Janssen I, Fortier A, Hudson R, Ross R: Effects of an energy-restrictive diet with or without exercise on abdominal fat, intermuscular fat, and metabolic risk factors in obese women. Diabetes Care 2002, 25: 431-438.

8. Geliebter A, Maher MM, Gerace L, Gutin B, Heymsfield SB, Hashim SA: Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects. Am J Clin Nutr 1997, 66: 557-563.

9. Bryner RW, Ullrich IH, Sauers J, Donley D, Hornsby G, Kolar M, Yeater R: Effects of resistance vs. aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. J Am Coll Nutr 1999, 18: 115-121.

10. Park SK, Park JH, Kwon YC, Kim HS, Yoon MS, Park HT: The effect of combined aerobic and resistance exercise training on abdominal fat in obese middle-aged women. J Physiol Anthropol Appl Human Sci 2003, 22: 129-135.

11. Wycherley TP, Noakes M, Clifton PM, Cleanthous X, Keogh JB, Brinkworth GD: A high-protein diet with resistance exercise training improves weight loss and body composition in overweight and obese patients with type 2 diabetes. Diabetes Care 2010, 33: 969-976.

12. Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK: American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc 2009, 41: 459-471.

13. Stiegler P, Cunliffe A: The role of diet and exercise for the maintenance of fat-free mass and resting metabolic rate during weight loss. Sports Med 2006, 36: 239-262.

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What is the best exercise for fat loss? Part III

For some reason it makes intuitive sense to me that high intensity exercise is better for fat loss than low intensity, but I do not quite know how this came to make sense.

High intensity exercise will cause a primary burning of glucose and so high intensity exercise will make our muscles better at taking up and burning glucose thus theoretically making us more glucose tolerant. Then again, during low intensity endurance exercise we primarily burn fat. Endurance exercise will make us better at burning fat, and fat is undoubtedly the thing to burn if we want to lose weight.

Generally speaking high intensity exercise will increase our muscle-neuron cooperation, improve factors related to anaerobic fuel utilization, improve our glucose metabolism and if performed with some resistance, increase our muscle size and strength. Lower intensity exercise will improve our aerobic fuel utilization, increase blood flow by increasing numbers of capillaries and increase the number and size of mitochondria – the powerhouse of the cells that are responsible for burning fat.

In the 2001 version of the ACSM position stand “Appropriate Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults,” the authors could say little on the effect of exercise intensity [1]. Lucky for us, several studies have come out since then that help paint a clearer picture. Despite these recent publications, the new and updated 2009 ACSM position stand contain no discussion on exercise intensity at all and the subject seems forgotten [2].

No doubt, if physical activity is to affect weight loss or weight loss maintenance it invariably has to affect the very same factors we try to affect by diet. As overweight is a condition of excessive fat storage we want to increase lipolysis (the release of fat) from fat cells and we want to reduce storage of fat in the fat tissue. This does not however necessarily mean low intensity endurance exercise that increases our fat burning abilities.

The two major factors at play here are insulin and glucose levels in the blood. Because the fat tissue is guarding us against the dangers of high blood glucose by taking up excess it will grow as it is protecting us, making us burn glucose to reduce blood levels and storing fatty acids for later as they pose no immediate threat. If our muscle and liver glycogen stores are full (as they will be with high carb diets and little exercise) excess carbohydrate intake will force the body to turn glucose into fat to get it out of the way.

It is well known that even a single exercise session is associated with a significant improvement in insulin-stimulated glucose uptake. Training, in making us better at taking up glucose, will also improve glucose uptake into the fat cells by increasing GLUT-4. This is a good thing.

The antidiabetic drug Metformin (Glucophage) for example will increase glucose uptake by fat cells by increasing GLUT-4 mRNA expression and cellular protein content, leading to increased GLUT-4 protein content in the plasma membrane. GLUT-4 is a glucose transporter which allows glucose to travel across membranes. Metformin also stimulates glucose oxidation in fat cells.

It is also likely that increased lipolysis and fat oxidation will reduce hunger. The result is that a greater amount of the energy needed to sustain your daily life will come from your own fat stores rather than from food. Increased lipolysis and fat oxidation may even make you want to move around more. I think Albert Pennington hit the nail on the head when he said, «Energy expenditure is an index of calorie nutrition at a cellular level.«

The Intensity
First let’s look at some studies. (If you find yourself fighting the urge to fall asleep, just skip to the conclusion)

Coker et al tested the differential effects of moderate (50% of Vo2max) versus high-intensity (75% Vo2max) exercise in 18 overweight (BMI=30) elderly (71ys). The training was endurance exercise designed to expend 1000kcal per week. There was no significant change in body weight, BMI or percent fat, but the high intensity group experienced a significant reduction in visceral fat and a significant increase in thigh muscle attenuation [3].

A study published in the latest European Journal of Internal Medicine, reports putting twenty-two women with type 2 diabetes in a supervised group exercise program for six months. The program combined endurance and resistance exercise and the duration and intensity of exercise for each subject was recorded. The subjects were then divided with respect to training volume in a high training volume group and a low training volume group [4].

Although exercise capacity did not change significantly during the training period, insulin sensitivity increased significantly and HbA1c decreased significantly from baseline in the high volume group but not in the low volume group. A large part of the improvement in insulin resistance was explained by exercise intensity. It is likely that an improvement in insulin resistance will affect the amount of fat mass lost over time.

Contrary to the above finding, Emmanuel G. Ciolac found that equal volume of high-intensity interval (aerobic interval training 80–90% of Vo2max) and moderate-intensity continuous exercise training (50–60% of Vo2max) elicited equal improvements in insulin sensitivity in healthy women [5].

Grediagin et al [6] did a small study where twelve untrained, moderately overweight women were randomly assigned to a high-intensity (80% Vo2max) or low-intensity (50% Vo2max) exercise group. The subjects trained four times per week for 12 weeks in sessions with duration sufficient to expend 300 kcal. The subjects were further instructed to maintain their normal diet and activity patterns. By the end of twelve weeks there were no significant between-group differences for change in weight, percent body fat, fat mass, fat-free mass, skin fold measurements or circumference measurements.

The above study however, because of its small number of participants may have type 2 error in it. Although the differences did not reach statistical significance, the mean weight loss was 0.7 lb for the high-intensity group and 3.3 lb for the low-intensity group. Hydrostatic data revealed that both groups lost 5.0 lb of fat, but the high-intensity group gained more than twice as much fat-free mass (4.3 vs 1.8 lb).

Brian Irving and colleagues [7] did a study where twenty-seven middle-aged obese women (51ys, BMI=34) with the metabolic syndrome completed one of three 16-week aerobic exercise (walk/run) interventions: no-exercise training (Control), low-intensity exercise training (<lactate threshold 5days per week) and high-intensity exercise (>lactate threshold, 3days per week). Exercise time was adjusted to maintain caloric expenditure (400 kcal per session). The researchers found that high-intensity significantly reduced total abdominal fat, abdominal subcutaneous fat and abdominal visceral fat. These changes were not observed in the control or the low intensity group.

Similar to Irving, Bryner et al [8] found that in 15 women randomized to exercise with a mean heart rate of 132 or 163 for 45 minutes 4 times per week, high intensity did cause a significant reduction in percent body fat not observed in the low intensity group.

Nicklas et al [9] randomized 112 overweight and obese postmenopausal women to one of three 20-week interventions of equal energy deficit: calorie restriction, calorie restriction plus moderate-intensity aerobic exercise (treadmill walking at an intensity of 45-50% heart rate reserve), or calorie restriction plus vigorous-intensity exercise (70-75%). Exercise was 3 days per week.

The exercise groups lost significantly less lean mass than the diet only group. The vigorous intensity group increased Vo2max more than the other groups and changes in visceral fat were inversely related to increases in Vo2max. However, the groups lost equal amounts of total and regional fat.

Slentz, who coauthored the Houmard study mentioned in the last post, reported that low-amount/moderate-intensity and low amount/vigorous intensity endurance training (i.e., activity equivalent to ~12 miles per week of walking or jogging) were equally effective in reducing percent body fat mass, waist circumference and abdominal circumference in overweight middle-aged adults. They also reported that high-amount/vigorous-intensity endurance training (activity equivalent to ~20 miles per week of jogging) was more effective in reducing percent body fat and fat mass compared with the two low-amount training groups [10].

These results are of course used to justify the claim that it’s the amount of calories burned or the volume of exercise that matters.

In a more recent trial Slentz et al [11] demonstrated that in middle-aged overweight/obese individuals who were randomized to three 8-month exercise programs: low amount/moderate intensity, low amount/vigorous intensity, or high amount/vigorous intensity, the moderate intensity improved pancreatic β-cell function more than vigorous intensities. However, vigorous intensity caused a 7% reduction in visceral fat whereas moderate intensity gave no reduction. Also, only the high-amount/vigorous-intensity group showed a decreased insulin response to a glucose challenge. There was no decrease in insulin response in the low amount/moderate intensity group that had the greatest improvement in insulin sensitivity index.

Whyte et al [12] tested the effect of 2 weeks of sprint interval training on ten overweight (BMI=31) men. The exercise comprised of 6 sessions of 4 to 6 repeats of 30-second Wingate anaerobic sprints on a cycle ergometer, with 4.5-minute recovery between each repetition. Despite the short intervention time, both waist and hip circumferences decreased compared with baseline.

It is important to remember that these acute (2 weeks) responses to exercise are not necessarily transferable to long term responses. However, acute responses are sometimes all we’ve got and should be considered.

Chambliss et al did a 1 year intervention study with four different exercise interventions as a part of a standard calorie restricted diet. They found no significant differences between low and moderate intensities on weight loss [13].

Jakicic et al [14] also did a 1 year study where 201 women were randomized to 1 of 4 exercise groups: vigorous intensity/high duration; moderate intensity/high duration; moderate intensity/moderate duration; or vigorous intensity/moderate duration. The participants also followed a low energy diet. The authors did not find any differences in weight loss after one year.

The conclusion
There are a few things I find important to keep in mind when interpreting results from exercise trials. First, an improvement in a factor related to metabolic health may not cause a significant short term effect on weight or fat mass. It is still theoretically plausible that improvements in fat mass may come in time because of the improvements in the related metabolic parameters. Simply speaking, I don’t expect big results on fat mass from any form of exercise lasting only a few months.

Also, some of these studies use intension to treat analyses, and so the actual effect of doing the different exercises is not reported.

All in all, and as far as I can tell, there is sufficient data to support a recommendation of high intensity exercise over low intensity exercise for maximal loss of body fat. Not all trials find a difference, but several do, and some of those that do not find anthropometric differences find metabolic differences likely to affect weight loss over time. In addition, risk factors for cardiovascular disease are improved more with high intensity than low intensity.

Although most studies looking at exercise intensity in relation to fat loss use endurance exercises some studies still show an increased growth or reduced loss of muscle tissue with high intensity training. In fact, it is quite possible to lose fat while gaining muscle even while doing low resistance high intensity exercise. I think the whole topic of gaining muscle while losing fat deserves a separate post so…

Next: The losing of fat, not muscles.

References:

1. Jakicic JM, Clark K, Coleman E, Donnelly JE, Foreyt J, Melanson E, Volek J, Volpe SL: American College of Sports Medicine position stand. Appropriate intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc 2001, 33: 2145-2156.

2. Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK: American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Exerc 2009, 41: 459-471.

3. Coker RH, Williams RH, Kortebein PM, Sullivan DH, Evans WJ: Influence of Exercise Intensity on Abdominal Fat and Adiponectin in Elderly Adults. Metab Syndr Relat Disord 2009.

4. Segerstrom AB, Glans F, Eriksson KF, Holmback AM, Groop L, Thorsson O, Wollmer P: Impact of exercise intensity and duration on insulin sensitivity in women with T2D. Eur J Intern Med 2010, 21: 404-408.

5. Ciolac EG, Bocchi EA, Bortolotto LA, Carvalho VO, Greve JM, Guimaraes GV: Effects of high-intensity aerobic interval training vs. moderate exercise on hemodynamic, metabolic and neuro-humoral abnormalities of young normotensive women at high familial risk for hypertension. Hypertens Res 2010, 33: 836-843.

6. Grediagin A, Cody M, Rupp J, Benardot D, Shern R: Exercise intensity does not effect body composition change in untrained, moderately overfat women. J Am Diet Assoc 1995, 95: 661-665.

7. Irving BA, Davis CK, Brock DW, Weltman JY, Swift D, Barrett EJ, Gaesser GA, Weltman A: Effect of Exercise Training Intensity on Abdominal Visceral Fat and Body Composition. Med Sci Sports Exerc 2008.

8. Bryner RW, Toffle RC, Ullrich IH, Yeater RA: The effects of exercise intensity on body composition, weight loss, and dietary composition in women. J Am Coll Nutr 1997, 16: 68-73.

9. Nicklas BJ, Wang X, You T, Lyles MF, Demons J, Easter L, Berry MJ, Lenchik L, Carr JJ: Effect of exercise intensity on abdominal fat loss during calorie restriction in overweight and obese postmenopausal women: a randomized, controlled trial. Am J Clin Nutr 2009, 89: 1043-1052.

10. Slentz CA, Duscha BD, Johnson JL, Ketchum K, Aiken LB, Samsa GP, Houmard JA, Bales CW, Kraus WE: Effects of the amount of exercise on body weight, body composition, and measures of central obesity: STRRIDE–a randomized controlled study. Arch Intern Med 2004, 164: 31-39.

11. Slentz CA, Tanner CJ, Bateman LA, Durheim MT, Huffman KM, Houmard JA, Kraus WE: Effects of exercise training intensity on pancreatic beta-cell function. Diabetes Care 2009, 32: 1807-1811.

12. Whyte LJ, Gill JM, Cathcart AJ: Effect of 2 weeks of sprint interval training on health-related outcomes in sedentary overweight/obese men. Metabolism 2010, 59: 1421-1428.

13. Chambliss HO: Exercise duration and intensity in a weight-loss program. Clin J Sport Med 2005, 15: 113-115.

14. Jakicic JM, Marcus BH, Gallagher KI, Napolitano M, Lang W: Effect of exercise duration and intensity on weight loss in overweight, sedentary women: a randomized trial. JAMA 2003, 290: 1323-1330.