Studies suggest that consumption of dairy foods is beneficial to the body weight. For example, in a recent study, researchers investigated the dairy intake of a large group (18,438) women, over 45 years, who were free from cardiovascular disease, cancer and diabetes. Only women with a body mass indices of between 18 and 25 kg/m2 were selected to take part in the study. The women were then followed prospectively for 11.2 years and their body mass indices assessed during this time period, where they were categorised as normal weight (BMI: 18.5 to 25 kg/m2), overweight (BMI: 25 to 30 kg/m2),or obese (BMI >30 kg/m2). During the follow up period about 8000 of the women became overweight or obese. Assessment of the changes in body weight with the intake of dairy products showed that intakes of high fat dairy products, but not low fat dairy products, was associated with less weight gain in the women. However, dietary supplements of vitamin D or calcium were not associated with protection from weight gain.
Conjugated linoleic acid is a fatty acid found in small amounts in dairy foods. It is produced in stomach of ruminants through bacterial fermentation of linoleic acid and from there accumulates in the meat and milk. Conjugated linoleic acid has been shown to have an insulin sensitising effect in humans and animals, and this may explain its protective effects against the development of weight gain and obesity. Conjugated linoleic acid is also available as a supplement and clinical trials show these supplements to have insulin sensitising and weight loss effects. Another possible property of conjugated linoleic acid is an anti-cancer effect, although much of the evidence from this comes from animal models. Milk may also be beneficial to weight loss because casein, the main protein in milk, curdles in the stomach. This may produce beneficial glycaemic effects, which over time could increase insulin sensitivity and induce weight loss.
Dairy might be a weight loss food because it contains a number of factors and properties that suggest that its regular consumption would be beneficial. Both vitamin D and calcium have been suggested to be responsible in part for this effect. In this study calcium and vitamin D supplements were not associated with a protective effects against weight gains (note that this study was conducted in the United States where milk is fortified with vitamin D). This may suggest that vitamin D and calcium are not responsible for the weight loss effects observed with milk consumption, although this possibility cannot be excluded by one study, as other studies do show possible weight loss effects for these components. Milk also contains conjugated linoleic acid, and this fatty acid has been shown to have fat loss effects in humans. The fact that high fat, but not low fat, dairy products showed an association with reduced weight gain, may suggest that conjugated linoleic acid is the protective component in dairy with regards weight gain.
Eat Well, Stay Healthy, Protect Yourself
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