The Role of Dairy Foods in Weight Management

Abstract

Dietary calcium appears to play a pivotal role in the regulation of energy metabolism and obesity risk. High calcium diets attenuate body fat accumulation and weight gain during periods of over-consumption of an energy-dense diet and to increase fat breakdown and preserve metabolism during caloric restriction, thereby markedly accelerating weight and fat loss. This effect is mediated primarily by circulating calcitriol, which regulates adipocyte intracellular Ca²⁺. Studies of human adipocyte metabolism demonstrate a key role for intracellular Ca²⁺ in regulating lipid metabolism and triglyceride storage, with increased intracellular Ca²⁺ resulting in stimulation of lipogenic gene expression and lipogenesis and suppression of lipolysis, resulting in adipocyte lipid filling and increased adiposity. Moreover, the increased calcitriol produced in response to low calcium diets stimulates adipocyte Ca²⁺ influx and, consequently, promotes adiposity, while higher calcium diets inhibit lipogenesis, promote lipolysis, lipid oxidation and thermogenesis and inhibit diet-induced obesity in mice. Notably, dairy sources of calcium exert markedly greater effects in attenuating weight and fat gain and accelerating fat loss. This augmented effect of dairy products versus supplemental calcium has been localized, in part, to the whey fraction of dairy and is likely due to additional bioactive compounds, such as angiotensin converting enzyme (ACE) inhibitors in dairy, as well as the rich concentration of branched chain amino acids, which act synergistically with calcium to attenuate adiposity; however, these compounds do not fully account for the observed effects, as whey has significantly greater bioactivity than found in these compounds. These concepts are confirmed by epidemiological data as well as recent clinical trials which demonstrate that diets which include at least three daily servings of dairy products result in significant reductions in body fat mass in obese humans in the absence of caloric restriction and markedly accelerates the weight and body fat loss secondary to caloric restriction compared to low dairy diets. These data indicate an important role for dairy products in both the ability to maintain a healthy weight and the management of overweight and obesity.

• calcium
• dairy
• whey
• obesity
• adipocyte
• ACE inhibition
• branched chain amino acids

Key teaching points:

• Dietary calcium modulates circulating calcitriol (1,25-dihydroxyvitamin D) levels that in turn regulate intracellular calcium which affects fat metabolism in human adipocytes.

• Reducing calcitriol levels by increasing dietary calcium results in reduction of body fat in the absence of caloric restriction, substantially increases body weight and fat loss during caloric restriction and reduces weight and fat regain following successful weight loss.

• Dairy sources of calcium are markedly (50–100%) more effective than supplemental calcium in reducing body weight and body fat during caloric restriction. A portion of this additional anti-obesity bioactivity is attributable to the ACE-inhibitory activity of dairy and to the rich concentration of branched chain amino acids.

• This anti-obesity effect of dietary calcium/dairy is supported by cellular mechanistic studies, animal studies human epidemiological studies and clinical trials.

• Incorporating dairy into weight management regimens is associated with significant preservation of lean body mass during caloric restriction.

Key teaching points:

• Dietary calcium modulates circulating calcitriol (1,25-dihydroxyvitamin D) levels that in turn regulate intracellular calcium which affects fat metabolism in human adipocytes.

• Reducing calcitriol levels by increasing dietary calcium results in reduction of body fat in the absence of caloric restriction, substantially increases body weight and fat loss during caloric restriction and reduces weight and fat regain following successful weight loss.

• Dairy sources of calcium are markedly (50–100%) more effective than supplemental calcium in reducing body weight and body fat during caloric restriction. A portion of this additional anti-obesity bioactivity is attributable to the ACE-inhibitory activity of dairy and to the rich concentration of branched chain amino acids.

• This anti-obesity effect of dietary calcium/dairy is supported by cellular mechanistic studies, animal studies human epidemiological studies and clinical trials.

• Incorporating dairy into weight management regimens is associated with significant preservation of lean body mass during caloric restriction.