’I can’t tell you how wonderful it was’, she told me. ‘I walked into this room, and it was full of people like me. People who couldn’t sit still. People who had to move to think.’
I do some temp work at a local school. Noticed a boy in the top of a school yard tree the other day. I know he is one of those 14 year old boys who are completely unable to sit still for an entire class. That day, the first thing he did during break was to climb a tree. Because the tree was there.
If you place a running wheel in a rodent cage the animals will run. They will expend more energy and of course increase their food intake. But there is no need for rewards or incentives to get them to run. They thoroughly enjoy it. There is an inherent drive to run. It is in their nature.
A good fat metabolism will most likely make you active. Some people just can’t sit still. They are fat driven machines. If they can’t run they radiate heat and fidget non stop. These people are usually lean, which is the reason they can’t sit still.
Adam Kennedy and colleagues put mice on a ketogenic diet, a common obesogenic high-fat, high-sucrose diet, a 66% caloric restriction diet or control chow.
Mice on the ketogenic diet ate the same amount of calories as both the mice on control diet and the high fat/high sugar diet, but their weight dropped and stabilized at 85% of initial weight.
Analysis of energy expenditure in the high fat/high sugar and the ketogenic groups revealed an increase in energy expenditure in ketogenic diet animals. Total heat output was 15% higher in the ketogenic group.
Some nice quotes from the study authors.
Somewhat reduced exploratory activity was seen in HF [High Fat] animals compared with C-fed [chow] animals.
The somewhat surprising preservation of fat mass in calorie-restricted animals has been described previously.
Thus, although severe caloric restriction is known to cause fat mass loss in rodents, metabolic adaptations prevent fat mass loss during moderate CR in mice and even permit a small weight gain…
Insulin levels were somewhat reduced in calorie-restricted animals compared with the chow-fed group, whereas insulin levels in ketogenic diet-fed animals were dramatically lower to a level that was only 10% of that seen in the calorie-restricted group.
Give rats sugar, and they become passive, give them fat and they radiate heat. I am not sure if Kennedys rats had access to a wheel, but it would have been interesting to also have measured voluntary wheel running, which is easier to measure than exploratory activity.
In a somewhat interesting article entitled, The biological control of voluntary exercise, spontaneous physical activity and daily energy expenditure in relation to obesity: human and rodent perspectives, the authors note that:
…food consumption increases in the presence of wheels, at least in rodents.
I do not get leaner and leaner the more I exercise, and this seems to be quite a universal human trait. This means that there must be a compensatory mechanism, and this mechanism has to be increased food intake or decreased non exercise energy expenditure.
In studies of human subjects confined within metabolic chambers for 24h, Ravussin et al. found that SPA [Spontaneous Physical Activity] varied widely and was a rather strong positive predictor of DEE [Daily Energy Expenditure] (Ravussin et al., 1986). They commented (p. 1577) that: “Because the subjects were not allowed to carry out physical exercise such as isometric exercises or calisthenics, it is possible that such activity represents an unconscious need to be active.” The implication is that forced reduction in voluntary exercise may lead to an increase in other types of physical activity.
We move to little and this is making us fat. At least this is what those less informed are trying to convince us.
Westerterp and Speakman provide evidence that physical AEE [Activity Energy Expenditure] has not declined over the same period that obesity rates have increased, and argue that it is unlikely that decreased DEE has been a major contributor to the human obesity epidemic.
Even though obesity rates seem to increase universally, reduced physical activity do not seem to be a universal phenomenon. In Canada and Finland physical activity trends seem to be increasing while USA has hit a plateau. England and Australia though seem to have decreasing physical activity trends.
Based on this retrospective application of the energy balance equation, many investigators and public health officials have used the same energy balance equation in a prospective manner to predict that the obesity epidemic can be addressed by initiating changes in energy expenditure or energy intake as small as 25–50 kcal/day. From the energy expenditure side of the equation, 25–50 kcal/day can be spent by walking an additional 750–1500 steps per day. From the energy intake side of the equation, energy intake can be reduced by 25–50 kcal/day or by eating one less cookie, or forkful of food each day. Although this use of a valid retrospective application of the energy balance equation to a prospective prediction appears quite valid, it is not an equivalent situation. The prospective application of the energy balance equation for a single change in energy intake assumes that energy expenditure will not change in response and that a simple change in energy expenditure assumes that energy intake will not change in response. Evidence, however, does not support this assumption.
The world is a funny place, but exercise will not make a fat person lean and simply eating less is a poor weight loss strategy. This, at least, we know.