The problem of food restriction and weight loss.

Weight cycling is a common problem for chronic dieters. People lose weight by dieting, which often involves restricting food intake, and find that after they go off the diet, they end up weighing more than they did before they started. This cycle can be very frustrating for people desperately trying to lose weight.

A recent article in the American Journal of Clinical Nutrition reports that in the modern environment, restriction of food intake may indeed prove to be counter productive in the quest for weight loss. The food intake, weight and metabolic rate of eight volunteers was measured away from the pressures of the outside world in a 'mini-world' called Biosphere 2, a structure made of glass and steel, designed to mimic the ecology of earth. The volunteers found difficulties in growing their own food, which meant that energy intake was restricted, however they were still expending a lot of energy.

The subjects lost an average of 9kg in the 2 years spent in the Biosphere, and when released their metabolic rate was shown to be below that estimated for their new body weights. Six months after returning to normal life, they had returned to normal weight, but their metabolic rate remained significantly lower than it was at the beginning of the experiment. This suggests a permanent change in metabolism which will practically guarantee that they end up weighing more than when they entered the Biosphere. These findings may support the notion that food restriction is indeed counter productive in weight loss. In so far as there was a loss of lean mass, however, this may be reversible as a basis of energy metabolism and requirements.

Note: Biosphere 2 was an interesting project in human biology but limitations are that it did not work out to be as ecologically self contained as originally planned. Therefore it was not an ideal environment to an conclusions drawn from the study must be assessed critically .

One tried and true method to increase weight loss and improve overall health is good old-fashioned exercise. For centuries it has been known that regular physical activity has some benefit on health, but it has become more pronounced since the advent of technology, which has seen marked decreases in the activity levels of the population. New research has shown that regular physical activity before the age of 30 can decrease natural height loss by as much as 50% later in life. Benefits with diabetes and arthritis have also been seen.

It is recommended that we do some kind of exercise at least every couple of days. Research shows that the benefits of physical activity wear off in time, therefore some sort of exercise should be carried out almost daily as is recommended by the National Physical Activity Guidelines.

References:
Weyer, C. et.al. Energy metabolism after 2y of energy restriction: the Biosphere experiment. AJCN, 2000. 72(4): 946-53.
Goldberg, L. Elliot, DL. The healing power of exercise: your guide to preventing and treating diabetes, depression, heart disease, high blood pressure, athritis and more. John Wiley and Sons, NY, 2000.

More information
120 year diet. Quantum, ABC television. Thursday April 12, 2001.

Last Updated: May 2, 2001.