According to the current paradigm, weight loss is caused by reducing energy intake (or increasing energy expenditure) in order to cause a negative energy balance. To question the ‘fact’ that a negative energy balance is required to cause weight loss leaves oneself open to derision because this energy balance meme has become ingrained in the psyche of the population. Evidence for weight loss from studies involving the exposure of subjects to a low calorie diet and exercise can be found adorning the scientific literature, and anecdotally people believe that dieting causes weight loss because they have experienced it themselves. However, if we look at more detail at the nuances of these studies and anecdotal reports, what we find is a half-truth wrapped in a lie. Short-term it is possible to cause weight loss by inducing a negative calorie balance through diet and exercise. However, in the long-term a negative energy balance strategy of weight loss is destined to fail because it does not address the root cause of the original weight gain.
When familiarity is reached with the nutritional literature it becomes possible to see a pattern in weight loss studies. They are usually of short duration and poorly controlled because of the inclusion of too many variables. The short duration of the studies is often explained as a requirement due to the difficulty and expense of performing longer term studies. However, the reality of the situation to the more cynically minded (like myself) is that short term studies are used because longer term studies do not result in net weight loss. When longer term studies have been performed, they generally show initial weight loss, followed by a gradual deterioration in body composition as the weight is slowly regained. The lack of controlled variables within many studies muddies the water and is problematic because with caloric restriction, the subjects often also receive healthier foods and nutritional advice. It is therefore it is not possible to state that it is the negative energy balance that is the cause of the weight loss.
Anecdotally evidence fits with the pattern seen in studies. Short term weight loss is often observed, but this weight is regained over time. In addition, individuals usually make improvements to the diet at the same time as restricting energy intake (such as replacing cakes and biscuits with healthier alternatives), and for this reason it is not possible to state that the negative energy balance was the cause of any weight loss. Further, the obesity disease is characterised by an accumulation of body fat. When we refer to being overweight, that weight is fat weight. Logically therefore weight loss should actually mean fat loss. However, this slight nuance in meaning if often ignored by advocates of energy restrictive diets and aerobic exercise. Initially on such regimens, weight loss is possible, but the question we should ask is how much of that weight is fat? Ideally we would want it all to be fat as loss of lean tissue during periods of negative energy balance may be the primary driver for future weight regain.
In fact what we actually find is that perhaps as much as half or more of the weight lost is actually skeletal muscle, and often less than half is fat. The more restrictive the energy intake, generally the more skeletal muscle is lost. This loss of skeletal muscle is the main reason such diets fail, because the loss of skeletal muscle is associated with a reduction in the resting metabolic rate, and this increases the likelihood of future weight regain when a more normal energy intake is consumed. When this weight is regained it is usually all as fat. Therefore a negative energy balance causes a period of weight loss (muscle and fat) followed by weight regain (just fat), and this over time during successive periods of dieting causes a deterioration in body composition and a lowering of the resting metabolic rate. It is now acknowledged that the metabolic damage caused by even one period of forced energy restriction may last for many years and may in some cases be permanent.
RdB
