The current mainstream opinion is that only energy restriction, either through increased exercise or decreased food intake, can ultimately result in weight loss. However, despite dogmatic defence of this opinion, the nutritional literature is increasingly highlighting diet quality as being the primary driver of fat loss. It is logical that a high quality diet can cause fat loss, because evidence suggests that low quality nutrition in the form of the Western diet is a primary driver of weight gain. Western food is both deficient in micronutrients and contains metabolic poisons such as fructose and trans fatty acids, and the combination of these factors inhibits correct metabolic flux and leads to metabolic dysfunction. Under these conditions energy restriction is not able to cause effective fat loss because the energy metabolism pathways, the energy regulatory systems and the appetite control systems are some of those affected by the metabolic dysfunction. Trying to force weight loss under such conditions can never be effective.
However, that is not to say that energy restriction does not cause weight loss. Weight loss is a known phenomenon of calorie restriction. However, often such weight is to a large extent made up of skeletal muscle, and this had detrimental long-term effects on the health of the individual, and also greatly increases the risk of future weight gain in the form of adipose tissue. Exercise can be effective against the accumulation of body fat, but this must come with dietary improvements. However, the positive effects of exercise likely relate not to its calorie burning effects, but to its ability to increase skeletal muscle mass. In studies looking at combinations of dietary quality improvements and physical activity, generally subjects who perform physical activity are worse off than those who make dietary improvements. For example, in a recent study1, researchers assessed the effects of improvements in diet quality and physical activity on the abdominal obesity displayed by subjects with metabolic syndrome (a condition of metabolic dysfunction caused by poor diet).
The subjects were given a diet to follow for one year based on the guidelines of the Dietary Approaches to Stop Hypertension (DASH) Diet. Assessment of the physical activity and dietary records of the subjects showed that both diet quality and physical activity levels were both independently associated with reductions in body weight, fat mass and visceral adipose tissue and thigh fat mass, irrespective of calorie restriction. However, while physical activity and diet quality improvements acted synergistically to cause improvements in body composition, those who had large improvements in diet quality but performed little physical activity had greater reductions in visceral adipose tissue than those who performed large amounts of physical activity but did not greatly improve their diet. These results suggest that energy intake is not an important variable in fat loss, and that physical activity is more effective when combined with dietary improvements. The fact that dietary improvements alone cause fat loss, suggest it is the pivotal factor in fat loss.
RdB
