Dairy enhances weight loss and body composition changes during energy restriction

Healthy foods from the food groups image


By Dr Welma Stonehouse, Research Scientist, Health & Biosecurity, CSIRO & Dr Malcolm Riley, Research Scientist, Health & Biosecurity, CSIRO

Dairy foods are often avoided because of the notion that it contributes to weight gain 1,2. But, contrary to this perception, dairy consumption may actually enhance weight loss and body composition changes when consumed as part of an energy restricted diet by 18-50 year old adults as was recently confirmed in a comprehensive scientific review by Stonehouse et al. 3.

The general goal for optimal weight loss is to reduce body weight by reducing fat mass while minimising loss of lean mass (or muscle and other non-fat body components). Energy restricted diets often result in a concurrent unfavourable lean mass reduction, accounting for ~20% of total weight loss4. Retaining lean mass, particularly its skeletal muscle component, is important for regulating resting energy expenditure, protein metabolism and postprandial glucose uptake5

Dairy contains several nutrients and bioactive components that may assist in achieving this goal. In particular, dairy is a rich source of calcium that reduces absorption of fat 6; proteins (whey and casein) that promote muscle protein synthesis 7,8 and regulate appetite 9; and fatty acids, specifically medium-chain fatty acids and conjugated linoleic acid, that affect energy balance through reduced fat synthesis (lipogenesis), increased fat breakdown (oxidation) and by regulating appetite 10,11

Stonehouse et al.3 performed a systematic review and meta-analysis of randomized controlled trials (RCTs) identified by searching 5 global databases of scientific journals to investigate the effects of consuming dairy food or supplements during energy restriction on body weight and composition in 18-50 year olds. The studies that were largely undertaken in women (90% were women) showed that consuming dairy food or supplements as part of an energy restricted diet resulted in ~1.5 kg greater loss in fat mass compared to those consuming a diet low in dairy. Participants who consumed more dairy also managed to retain 75% more lean mass compared to those consuming low dairy diets. 

The results did not differ between studies that used whole dairy foods versus dairy supplements, or between studies that specified the use of low-fat or skimmed dairy products compared to those that did not specify the product type. Hence, either regular fat dairy food, low fat dairy food or dairy supplements can be consumed as part of an energy restricted dietary intake to get additional fat loss benefit.

The results were achieved by consuming more than two servings of whole dairy food daily or 20-84 g of whey protein per day for an average of 16 weeks. A serving of dairy equals a glass of milk, 200g yoghurt or 40g cheese.

Since the majority of participants examined in the studies were women, further research in men is required to investigate whether there is a difference by sex.
In conclusion, consuming whole dairy food or dairy whey protein supplements as part of an energy restricted diet assisted with body weight and fat mass loss while better preserving lean mass in 18-50yr old adults. 

References

1. Horwath CC, Govan CH, Campbell AJ, Busby W, Scott V. Factors influencing milk and milk product consumption in young and elderly women with low-calcium intakes. Nutr Res. 1995 Dec;15(12):1735-45.
2. Nolan-Clark DJ, Neale EP, Probst YC, Charlton KE, Tapsell LC. Consumers' salient beliefs regarding dairy products in the functional food era: a qualitative study using concepts from the theory of planned behaviour. BMC Public Health. 2011;11:843.
3. Stonehouse W, Wycherley T, Luscombe-Marsh N, Taylor P, Brinkworth G, Riley M. Dairy Intake Enhances Body Weight and Composition Changes during Energy Restriction in 18-50-Year-Old Adults-A Meta-Analysis of Randomized Controlled Trials. Nutrients. 2016;8(7).
4. Krieger JW, Sitren HS, Daniels MJ, Langkamp-Henken B. Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression. Am J Clin Nutr. 2006 Feb;83(2):260-74.
5. Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012 Dec;96(6):1281-98.
6. Christensen R, Lorenzen JK, Svith CR, Bartels EM, Melanson EL, Saris WH, et al. Effect of calcium from dairy and dietary supplements on faecal fat excretion: a meta-analysis of randomized controlled trials. Obes Rev. 2009 Jul;10(4):475-86.
7. Hector AJ, Marcotte GR, Churchward-Venne TA, Murphy CH, Breen L, von Allmen M, et al. Whey protein supplementation preserves postprandial myofibrillar protein synthesis during short-term energy restriction in overweight and obese adults. J Nutr. 2015 Feb;145(2):246-52.
8. Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol (1985). 2009 Sep;107(3):987-92.
9. Dougkas A, Reynolds CK, Givens ID, Elwood PC, Minihane AM. Associations between dairy consumption and body weight: a review of the evidence and underlying mechanisms. Nutr Res Rev. 2011 Feb 15:1-24.
10. Feltrin KL, Little TJ, Meyer JH, Horowitz M, Smout AJ, Wishart J, et al. Effects of intraduodenal fatty acids on appetite, antropyloroduodenal motility, and plasma CCK and GLP-1 in humans vary with their chain length. Am J Physiol Regul Integr Comp Physiol. 2004 Sep;287(3):R524-33.
11. Mumme K, Stonehouse W. Effects of medium-chain triglycerides on weight loss and body composition: A meta-analysis of randomized controlled trials. J Acad Nutr Diet. 2014;In press.
12. Onakpoya IJ, Posadzki PP, Watson LK, Davies LA, Ernst E. The efficacy of long-term conjugated linoleic acid (CLA) supplementation on body composition in overweight and obese individuals: a systematic review and meta-analysis of randomized clinical trials. Eur J Nutr. 2012 Mar;51(2):127-34.