Observations studies show that those with the highest intakes of dairy products have the lowest body weights. Observational studies have also shown that those with the highest calcium intakes have the lowest body weights. Clinical studies involving supplementation with dairy and calcium have shown beneficial weight loss effects for both calcium and dairy products. Taken as a whole this suggests that some or all of the fat loss effects observed through high intakes of dairy products might be due to the calcium content. The traditional viewpoint is that calcium is required for strong bones, and this is true as calcium makes up a large proportion of the matrix of bone tissue. However, more recently, novel metabolic effects have been described for calcium and these include a diverse and integral cell signalling role that is involved in cell regulation and growth. Such effects may explain the role of dietary calcium and dairy products in the maintenance of correct body weight and the prevention of obesity.
Studies investigating the effects of dairy food have observed beneficial fat loss effects. These effects are consistent with a role for calcium in the metabolic regulation of body fat. For example, in one study1, researchers randomised overweight subjects to receive one of three diets during a 500 kcal energy restriction diet that included an exercise regimen of resistance and aerobic training that lasted for 16 weeks. Diet 1 contained high protein levels (30 % of energy) with a high dairy content (15 % of energy), diet 2 contain adequate protein (15 % of energy) with adequate dairy (7.5 % of energy) while diet 3 contain adequate protein (15 % of energy) with low dairy (<2 % of energy). Between weeks 8 and 16, the high protein high dairy group lost significantly more body fat than the other groups and during this time the subjects also gained significantly more muscle tissue. This caused the body composition of the high protein high dairy group to have improved the most improvement by the 16 week time point.
This high protein high dairy group also lost more trunk fat and more visceral fat compared to the other groups. The loss of visceral fat in all groups correlated with the intake of calcium and protein. These results therefore suggest that high protein high calcium diets may confer beneficial fat loss effects, particularly to visceral adipose tissue during exercise regimens. However, it could be that these effects are present even in the absence of exercise, as no control was performed in this study to assess this dimension. It is unlikely that calcium has a pharmacological action of fat loss as no evidence for such an effect exists. It is much more likely that the majority of Westerners have calcium deficient diets and supplementation with calcium or increases in dairy product consumption repletes the individual with calcium to restore a previously deficient state. One particularly line of reasoning suggests that calcium deficiency results in a decrease in insulin sensitivity and this in turn leads to weight gain and obesity.
RdB
