Exercise Helps Little to Lose Weight: Eating Less Is More Effective

I have a tendency to be overweight and, for a few years now, my blood glucose levels have put me on the verge of diabetes. I like food and my social commitments include it often. In addition, from time to time some tapas, a wine or the vermouth of Saturdays fall. Nothing of the other world, but enough to have to take control measures of the glycemia and the weight.

At dawn I pedal a good time on an exercise bike. When I started with this morning activity, yes, I lost a couple of kilos in two or three weeks. Later I prolonged the time of pedaling. I lost another two kilos. But since then, and I've been under this regime for almost two years, my weight remains stubbornly constant. No matter how much physical exercise I do, I can hardly reduce it. I cannot pedal for longer. The day does not give of itself and the night either.

This issue makes me uneasy for two reasons. To begin with its effects or, rather, its lack of them. It is disheartening to ride a good morning on a bicycle, pedal wildly for more than an hour and continue almost as it was. The only thing I get is to lose the days of work the weight gained during the weekend.

On the other hand, I am also bothered by the apparent lack of physiological logic of all this. I teach physiology and in the part of the program in which I treat the energy balance, I explain that when activity increases, metabolic expenditure increases. Therefore, if the absorption of energy in the form of food is constant, that greater metabolic activity would cause a reduction of the energy available for growth. To the point, even, of becoming negative.

Does the energy balance not work?

It turns out that the body adapts to that situation and loses less mass than would be expected. I usually go cold, except on the warmest days of the year. And I spend more cold the mornings in which I have done intense physical exercise. That's why I think that what I make him pay in exercise, my metabolism is charged in the form of heat: it makes me go cold.

According to the anthropologist Herman Pontzer, of the Duke University of the USA, when increasing the long-term physical activity the daily energetic cost also rises, but less than it would be expected. In addition, as activity increases, the total daily expenditure increases less and less, until it becomes almost constant. That means that, if that expenditure is more or less constant and the body develops more physical activity, other spending chapters have to be reduced. This reduction, in principle, occurs in non-essential functions.

The hypothesis of Pontzer -who has worked in integrated teams also by physicians and physiologists-, predicts that physical activity exerts a reduction in other physiological activities and that these reductions have, in addition, beneficial effects for health. Of course, when the activity is very intense, these effects would become negative.

With moderate levels of exercise, the physiological activities whose activity would be reduced would be those that are not essential to survive. Some of the thermal regulation, somatic growth and those related to reproduction would fall into that category. In fact, high levels of physical activity alter the ovarian cycle, cause a decrease in sperm production, lower blood levels of sex hormones and reduce libido.

Under conditions of very high activity the effects on reproductive function are accentuated. In addition, the functioning of the immune system and the repair activities of damaged structures would also suffer. That's where the negative effects on health would come from.

From the above it follows that, although it is healthy to maintain moderate levels of physical exercise on a regular basis, this activity does not have the slimming effects that are usually attributed to it. To control the weight, the control of the intake is more effective. Although it is not easy or, as we know, your results are what you would expect.

As with physical activity, the organism also adapts to the shortage of food. It decreases, in this case, the speed of the vital processes. Metabolic activity is also reduced, low energy expenditure. The body temperature also suffers: by reducing the food ration is usually more cold. Eating less leads to a slower and, to a certain extent, more efficient physiological life.

All this is attributed to the very likely positive effect of caloric restriction on longevity. But that, for those of us who have the Damocles sword of overweight and type II diabetes on our heads, is bad news.

I'm not the one to advise anyone about their habits, but I do not mind telling you what my option has been:

  • As less than before and I put more care in what I eat, but I confess that from time to time I give myself a tribute.
  • I do a moderate physical activity, the equivalent of 150 km per week on a stationary bike, and I walk whenever I have the chance.