The first hint that calcium could promote weight loss came during the first-ever IASO Congress on Obesity held in South Africa in October 2004. More than one speaker at the Congress mentioned evidence linking calcium and/or diary products (which are our best source of dietary calcium), to improved weight loss.
Since then additional studies have produced more support for the theory that increasing calcium and dairy intake when slimming, will increase weight loss. Among them is an investigation carried out in the US in 34 overweight subjects using an energy-reduced diet to lose weight.
The energy content of the diets had been reduced by just over 2000kJ a day and subjects were randomly assigned to either eat three servings of low-fat yoghurt or three servings of gelatin a day for 12 weeks. The difference in calcium intake was that the yoghurt subjects ingested 1100mg a day, while the gelatine subjects only ingested 500mg of calcium a day.
The participants who ate yoghurt three times a day lost significantly more body weight, significantly more body fat and experienced significantly greater reductions in waist circumference (a measure that is used to check how much abdominal fat is lost).
Besides improved weight loss and body-fat reduction, inclusion of fat-free dairy products in slimming diets has the following added advantages:
- prevention of bone loss that accompanies conventional slimming regimens, thus also counteracting osteoporosis;
- a reduction in blood pressure for patients with hypertension.
How does it work?
At present researchers aren't sure why eating more dairy products or calcium will reduce weight. There are various theories, for example that low calcium intakes cause vitamin D to promote fat production and prevent fat breakdown. By increasing calcium intake, this negative effect can be counteracted and fat production is reduced, while fat breakdown is promoted.
Other theories state that dairy foods contain conjugated linoleic acid (CLA), which may promote fat breakdown.
So although nutritionists aren't quite sure why increasing calcium and/or dairy intake should promote weight loss, the results all point in this direction and can be used to improve the effect of slimming diets.
The following dairy foods can be used to increase your calcium and/or dairy intake when you're slimming:
- Fat-free or skimmed milk
- Fat-free or skimmed milk yoghurt (the plain, unflavoured varieties are most advantageous as flavoured yoghurts may have a higher energy content)
- Fat-free or low-fat cottage cheese
- Fat-free sour milk or maas
Although other cheeses are also rich in calcium, they are generally high in fat and this high fat content could hamper weight loss.
Most fad diets don't permit the use of dairy products, for example the Atkins diet prohibits the use of milk, yoghurt and cottage cheese. Other extreme diets or semi-starvation diets also tend to cut out all dairy products.
In the light of these research findings, such prohibitions of the use of dairy foods are non-productive, and just another indication that these diets are mostly illogical and unbalanced.
What you can do
If you're on a slimming diet that works for you, but you find that your weight loss is slowing down, try adding three servings of fat-free milk, yoghurt or cottage cheese to your diet. You can substitute the dairy products for other protein foods such as meat or eggs.
If you need to lose weight and have problems with high blood pressure, try using the DASH diet, which makes use of plenty of fat-free dairy products and is rich in calcium.
Ironically, dairy products are often the first foods that many people cut out of their diets when they want to lose weight. Don't. Include these foods but use fat-free or low-fat varieties and you will promote weight loss.
- (Dr I.V. van Heerden, DietDoc, updated December 2008)
(Reference: Arbor Clinical Nutrition Updates, 2005 (May), Issue 207, 1-3)