No effect of dietary calcium on body weight of lean and obese mice and rats

Recent epidemiological and animal studies have led to the hypothesis that low dietary calcium intakes contribute to obesity. Here, we evaluated whether calcium influenced the body weight of normal-weight and obese rodents. All experiments involved female C57BL/6J mice or Sprague-Dawley rats fed normal- or high-energy-density diets (3.8 or 4.7 kcal/g). Calcium intake was manipulated by allowing mice to drink sweetened 30 mM CaCl2 solution or feeding mice and rats diets differing in calcium content (0.2%, 0.6%, or 1.8% Ca2+). Blood samples were taken from rats to confirm that the diets had their intended effects on metabolism. There were no effects of the calcium manipulations on energy intake, body weight, or carcass fat content and no simple relation between calciotropic hormones and body weight. One experiment found a significant decrease in body weight gain of lean and obese rats fed the 1.8% Ca2+ diet, but we suspect that this was due to forced consumption of the unpalatable diet, reducing growth. These studies provide little support for the hypothesis that dietary calcium contributes to the etiology or maintenance of obesity.