Dairy and Healthy Weight in Adults

The evidence

A 2019 meta-analysis of 30 randomized controlled trials by Sochol et al. evaluated the effect of dairy food consumption on insulin resistance, body weight and waist circumference.¹ The authors concluded that dairy food consumption, especially low-fat dairy products, has a beneficial effect on all of these parameters. Compared to the control, the high dairy food interventions led to a:

• Greater reduction in body weight and waist circumference;
• Greater reduction in insulin resistance as measured by the homeostatic model assessment of insulin resistance (HOMA-IR).

A 2018 meta-analysis of 37 randomized controlled trials by Geng et al. explored dairy food consumption, weight and body composition.² This study included data from 184,802 adults. The findings support a beneficial effect of dairy products on body weight, body fat, lean mass and waist circumference in the context of caloric restriction. 

• Overall, higher dairy consumption was associated with decreased body fat, decreased waist circumference and an increase in lean mass.
• Higher dairy interventions with energy restriction resulted in greater weight loss, lower body fat and waist circumference, and higher lean mass compared to controls.
• Higher dairy consumption without energy restriction increased body weight but did not change body composition compared to controls. This may be due to not controlling for calories in studies that used “ad libitum” dietary interventions.

In a 2016 meta-analysis of 27 randomized controlled trials, Stonehouse et al. assessed the relationship between dairy intake and body weight and composition during energy restriction among 1,278 overweight and obese adults 18-50 years old.³ The authors also assessed the quality of the evidence using GRADE guidelines. Compared to the control groups, those in the dairy groups:

• Had a greater reduction in body weight and body fat mass;
• Had a ~75% smaller loss of lean mass.

They concluded there is a high degree of certainty for a relationship between dairy intake and greater reduction of body weight and fat mass in women under conditions of energy restriction. They rated the overall quality of the evidence as moderate since there were only 2 studies that included men.

A 2016 meta-analysis of 24 prospective cohort studies assessed the relationship between dairy intake and changes in measures of obesity, such as body weight, waist circumference and abdominal obesity, among adults.⁴ This meta-analysis found that:

• Total dairy intake was associated with decreased abdominal obesity and no weight gain;
• Whole-fat dairy was associated with reduced adiposity;
• Yogurt was associated with decreased body weight and waist circumference, as well as with a lower risk of abdominal obesity and becoming overweight.

A 2016 systematic review of randomized controlled studies and observational studies by Eales et al. investigated the effect of yogurt consumption on weight-related outcomes, including body weight, BMI, body fat, lean body mass and waist circumference.⁵ The authors concluded that consuming yogurt daily may facilitate loss of body fat.

• In observational studies, yogurt consumption was associated with lower body weight, lower BMI, lower body fat and smaller waist circumference.
• Results from randomized controlled trials showed either no effect or a favourable effect.

In 2012, Kratz et al. published the first systematic review of observational studies exploring the evidence related to high-fat dairy consumption and risk of obesity, cardiovascular and metabolic disease.⁶ This review concluded that high-fat dairy foods do not increase cardiometabolic risk. In fact, it found that high-fat dairy consumption is associated with a reduced risk of obesity.  

Conclusion

There is strong evidence that dairy consumption, particularly as part of an energy-restricted diet, can benefit adults trying to achieve a healthy weight and leaner body composition. Specifically, higher dairy intake as part of energy-restricted diets appears to help promote greater fat loss while preserving lean body mass.

Regular- and whole-fat dairy products appear to be associated with reduced adiposity and risk of obesity. More randomized controlled trials are needed to explore potential differences with respect to low- versus regular- and whole-fat dairy products.

Yogurt, in particular, appears to be associated with a lower risk of weight gain.

Additional research is needed to clarify how specific types of dairy products help in weight loss and maintenance.