In general terms, I believe in a eating a diet based on natural, unprocessed foods that are as ‘primal’ as possible. This means eating a diet in which core foods including (where desired) meat, fish, eggs, nuts, seeds, fruits and vegetables. I strongly oppose the idea that grains should be a staple in the diet, at least in part because of how disruptive they tend to be to blood sugar and insulin levels, and how this predisposes to all manner of ills including weight gain, heart disease and type 2 diabetes.
Another relatively recent addition to the human diet are dairy products such as milk, cheese and yoghurt. These foods can’t really be described as ‘primal’, in my view, though I’ve tended to have a relatively relaxed attitude to the consumption of at least some forms of dairy products. One thing going for some of them is that they are relatively rich in protein and fat, which in some ways emulates the nutritional make-up of primal foods such as meat and eggs.
Dairy products do induce insulin secretion, which could cause fat deposition. But their protein content will also induce the secretion of the hormone glucagon. One of glucagon’s main effects is to stimulate the conversion of triglyceride (the form fat is stored in the fat cells) into its constituent molecules, thereby facilitating lipolysis (fat breakdown). Also, unlike insulin, glucagon does not stimulate the uptake of sugar into the body’s cells. This helps restrict the amount of glucose available for the production of glycerol, which is required for the making of triglyceride, and the ‘fixing’ of fat in the fat cells. In other words, while protein increases insulin secretion, the rise in glucagon that comes at the same time mitigates the fat-forming effects of insulin.
Another factor that mitigates the insulin-provoking effects of dairy products relates to their calcium content. Consumption of calcium has been shown to paradoxically lower calcium level within fat cells, and this accelerates lipolysis [1].
There is considerable evidence linking higher intakes of calcium and dairy products with reduced body fatness [2]. It has been suggested that not just calcium, but other chemical constituents in dairy products somehow assist fat loss. There is evidence that supplementing the diet with dairy products (yoghurt) can enhance fat loss, including abdominal fat [3,4].
In light of this, I was interested to read a recently published study in which diets containing different amounts of protein and dairy products were tested in a group of overweight and obese women [5]. All women engaged in aerobic and/or resistance exercise, and ate a diet reduced in calories. The women were randomised to eat one of three diets:
1. High protein, high dairy (30 per cent of calories from protein, 15 per cent from dairy)
2. Adequate protein, medium dairy (15 per cent of calories from protein, 7.5 per cent from dairy)
3. Adequate protein, low dairy (15 per cent of calories from protein, < 2 per cent from dairy)
The trial lasted a total of 16 weeks.
All groups lost weight and body fat, but there were differences between the groups. Here are the highlights:
- Fat loss was greater with diet 1 than diets 2 and 3.
- Those eating diet 1 saw an increase in lean mass (e.g. muscle), while those eating diet 2 maintained lean mass and those eating diet 3 lost lean mass.
- Those eating diet 1 lost more ‘visceral’ fat than those eating diet 2 (visceral fat is fat found in and around the abdominal organs and is particularly strongly linked with ill-health).
- Loss of visceral fat was correlated with calcium and protein intakes – in other words, higher intakes of calcium and/or protein were associated with greater losses of visceral fat.
The authors of the study concluded that:
“Therefore, diet- and exercise-induced weight loss with higher protein and increased dairy product intakes promotes more favorable body composition changes in women characterized by greater total and visceral fat loss and lean mass gain.”
One of the major downsides to dairy, on the other hand, is that it’s a quite-common cause of food sensitivity reactions. My experience in practice is that pasteurised milk is the worse offender here, and I advocate raw dairy products (where available) if at all possible as these do seem to be much better tolerated.
I also prefer yoghurt as food over milk. I’ve found this to be much better tolerated, and this might have something to do with the fermentation of milk (as well as other foods) partially digests milk proteins and, to a degree, lactose, making it more digestible and less problematic in theory. If yoghurt is eaten, I recommend that this be in its full-fat form. A bowl of Greek yoghurt with some nuts and berries makes a good breakfast option for those seeking something nourishing and satisfying in the morning, and can be eaten safe in the knowledge that its likely to assist weight control over time.
References:
1. Zemel MB, et al. Regulation of adiposity by dietary calcium. FASEB Journal 2000;14:1132-1138
2. Teegarden D. Calcium intake and reduction of fat mass. J Nutr 2003;133:249S–251S
3. Zemel MB, et al. Dairy augmentation of total and central fat loss in obese subjects. Int J Obes (Lond). 2005;29(4):391-7
4. Zemel MB, et al. Effects of calcium and dairy on body composition and weight loss in African-American adults. Obesity Research 2005;13(7):1218-25
5. Josse AR 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 Jul 20. [Epub ahead of print]
