17 November 2008

Avocados a good diet food

Mention avocados and most people will tell you that these fruits are laden with fat and should be avoided by anyone trying to lose weight. But this isn't necessarily true.

Mention avocados and most people will tell you that these fruits are laden with fat and should be avoided by anyone trying to lose weight or by those who have raised blood fat levels.

However, research conducted at the Potchefstroom Institute of Nutrition at Potchefstroom University has found the opposite, namely that avocados can be used successfully in weight-loss diets. Furthermore, South African avocados proudly bear the "Heart Mark" bestowed by the Heart and Stroke Foundation of South Africa, which isn't what one would except for a supposedly high-fat food.

The Potchefstroom study
In the Potchefstroom study, 55 overweight male and female volunteers were randomly assigned to receive either 200g (1 avocado) a day in the place of 30g of other dietary fat, or no avocado (control group) as part of an energy-reduced diet.

The body mass index (BMI) values of the 11 men and 44 women who participated in the study varied from 27 to 44 kg/m2 (in other words, all the subjects were either overweight or obese). The subjects followed the experimental diets for six weeks.

Same weight-loss results
Both groups lost significant amounts of weight during the study, improved their BMIs and reduced their percentage of body fat.

What is of great interest, however, is that the weight loss in the group eating an avocado a day was similar to the weight loss in the group eating 30g of other fats instead of the avocado.

This shows that eating up to 200g of avocado a day in the place of other fats doesn't hamper weight loss when individuals are on a slimming diet.

Keep in mind that the experimental subjects substituted the 200g of avocado (which contains between 17 and 24g of fat per 100g) for 30g of other fats in their diet. They didn't add the 200g avocado to the 30g fat allowed in the slimming diet used in this study.

A good substitute
The Potchefstroom study shows that avocado, despite its high fat content of 17 to 24g per 100g, can be used successfully as a substitute for other dietary fats in energy-reduced diets intended to achieve weight loss.

Avocados are highly palatable and have a pleasant, creamy taste. They can be used in slimming diets as a substitute for margarine or butter on wholewheat/low-GI bread, for mayonnaise in salads, and for sour cream on baked potatoes.

They provide variety to weight-reduction diets and help dieters to stave off boredom that can lead to cheating and failure to stick to the slimming diet.

Avocados and the human heart
Why would the Heart and Stroke Foundation grant the Heart Mark to avocados and why would the American Dietetic Association classify avocados as "functional food" that have many health benefits?

The answers lie in the following nutritional properties of avocados:

  • Contrary to popular belief, avocados are cholesterol-free.
  • Despite their high fat content, the fat in avocados is mainly monounsaturated fat, which is beneficial to heart health. Monounsaturated fats lower "bad" LDL cholesterol and increase "good" HDL cholesterol - a win-win situation.
  • There is also some evidence that monounsaturated fats in foods can lower raised triglyceride levels.
  • Avocados are rich in protective nutrients such as vitamin E (a powerful antioxidant) and lutein (a compound belonging to the carotenoid family, which improves vision).
  • Avocados contain a compound called beta-sitosterol, which functions as an anti-cholesterol agent, thus protecting our bodies against excess cholesterol.
  • Avocados are rich in phytosterols that compete with dietary cholesterol for uptake by the human body, thus lowering blood cholesterol levels.

When all these positive effects and the high nutrient content of avocados are taken into account, it's understandable that health authorities view avocados in such a positive light.

If you suffer from raised blood cholesterol or triglyceride levels, then eating avocados (as well as other fruit and vegetables) makes good heart sense.

– (Dr I.V. van Heerden, DietDoc, updated November 2008)

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