The Role of Milk Products in Preserving Lean Mass During Weight Loss
Several studies to date, including a meta-analysis of randomized controlled trials, indicate that milk products may help promote healthy weight loss under caloric restriction by promoting fat mass loss while preserving lean mass such as muscle and bone.
In addition to producing the desired outcome of reduced fat mass, weight loss may also lead to the undesirable effect of losses in lean mass, including muscle and bone. It is important to preserve lean mass during weight loss, as these tissues contribute to:1
- Basal metabolic rate,
- Glycemic regulation,
- Lipid oxidation.
Studies on peri- and post-menopausal women and older men have shown that reduction in bone mass density induced by weight loss is more than double the annual rate of bone loss in weight-stable individuals.2 Additionally, bone loss resulting from intentional weight loss is often irreversible, even when weight is regained.3
The consumption of milk products during weight loss may promote an optimal body composition by supporting fat loss while preserving lean mass.
To learn more, visit Healthy Weight: Research Synopsis.
The Evidence
In a 2012 systematic review and meta-analysis of randomized controlled trials, Abargouei et al. examined the effect of milk product consumption on weight, fat mass, lean mass and waist circumference in adults.4 The meta-analysis consisted of 14 studies that included 883 adults aged 18 to 85 years and that compared conventional energy-restricted diets to high-dairy energy-restricted diets (3 servings of milk products). The findings showed that the high-dairy energy-restricted diets may result in more weight and fat mass loss and a greater decrease in waist circumference. Furthermore, a higher intake of milk products may lead to a gain in lean mass during weight loss.
The Improving Diet, Exercise and Lifestyle (IDEAL) for Women study was a randomized, controlled, parallel intervention trial of premenopausal overweight or obese women. The participants were assigned to one of the following 3 diets:
- High protein and high dairy diet: 6 to 7 servings of dairy products,
- Adequate protein and medium dairy diet: 3 to 4 servings of dairy products,
- Adequate protein and low dairy diet: 0 to 1 serving of dairy products.
It was concluded that increased intakes of dairy foods, dietary calcium and protein coupled with diet- and exercise-induced weight loss had a beneficial impact on total and visceral fat loss, on lean mass gain and on bone health biomarkers.5,6
Potential Mechanisms
The potential mechanisms underlying the favorable effect of milk products on body composition during weight loss have not been clearly elucidated. The mechanisms include both calcium-dependent and calcium-independent pathways.1
One of the most plausible mechanisms is that dietary calcium suppresses calcitriol levels, which decreases intracellular calcium. This subsequently affects adipocyte lipid metabolism by decreasing lipid synthesis.1,7
Alternatively, a potential mechanism is through the ability of calcium to prevent fatty acid absorption from the gastrointestinal tract. Calcium forms insoluble fatty acid soaps or binds bile acids in the gut. This weakens the formation of micelles, thus increasing fecal excretion of fat.1,7
Furthermore, milk products are also a rich source of other important components, including conjugated linoleic acids (CLA), medium-chain fatty acids and bioactive peptides, which may help regulate body weight, reduce fat mass, and preserve lean mass.7
Conclusion
Consuming milk products during weight loss may promote fat loss and preserve lean mass or even lead to a gain in lean mass.
The mechanisms that explain why milk products have a beneficial role in weight loss include the effect of calcium and other milk components such as CLA, medium-chain fatty acids and bioactive peptides.
More studies are needed to confirm the role of milk products in sustaining lean mass during weight loss and to provide definite answers on the potential mechanisms of this benefit.
References
- Phillips SM and Zemel MB. Effect of protein, dairy components and energy balance in optimizing body composition. Nestle Nutr Inst Workshop Ser 2011;69:97-108.
- Shapses SA and Sukumar D. Bone metabolism in obesity and weight loss. Annu Rev Nutr 2012;32:287-309.
- Pines A. Weight loss, weight regain and bone health. Climacteric 2012;15(4):317-9.
- Abargouei AS et al. Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials. Int J Obes (Lond) 2012;36(12):1485-93.
- Josse AR et al. Diets higher in dairy foods and dietary protein support bone health during diet- and exercise-induced weight loss in overweight and obese premenopausal women. J Clin Endocrinol Metab 2012;97(1):251-60.
- Josse AR et al. Increased consumption of dairy foods and protein during diet- and exercise-induced weight loss promotes fat mass loss and lean mass gain in overweight and obese premenopausal women. J Nutr 2011;141(9):1626-34.
- Dougkas A et al. Associations between dairy consumption and body weight: a review of the evidence and underlying mechanisms. Nutr Res Rev 2011:1-24.
Keywords: weight loss , calcium , conjugated linoleic acid , bioactive peptides
