For most of the past 40 years, dieters have been told to limit dietary fat, believing it leads to obesity and heart disease. Today, dieters hear messages to indulge in a very high-fat (ketogenic) diet and limit the carbohydrate-based foods that fuelled their low-fat diet.

Confusing? The fact is you can lose weight by limiting carbs and/or fat BUT the most effective to lose weight is through balanced nutrition.

Let’s look at the weight management picture, as we understand it to date. (Nutrition is an evolving science!)


Foods such as white bread, pasta, rice and potato (“carbs”) have been demonised as being fattening because they have a high glycaemic index. That is, they digest quickly and can spike blood glucose when eaten solo in 50-gram carbohydrate doses. This happens when the average (unfit) Australian devours a basket of warm dinner rolls. Blood glucose rises quickly; the pancreas secretes insulin to carry glucose from the blood into the muscles. Insulin can stimulate hunger, the desire to eat, and may contribute to weight gain.

How often would you eat rolls without butter or a large potato all by itself? Most likely, rarely. Eating “carbs” as part of a meal elicits a lower glycemic response than eating carbs by themselves. Protein and fat slow the carbohydrate conversion into blood glucose, thus blunting the glycemic response.

The advice given to the general public to limit high-glycemic foods often results in eating fewer calories (and losing weight). The advice can appropriately help stabilise blood glucose in women with polycystic ovary syndrome (PCOS), and unfit people with obesity, pre-diabetes, and Type II diabetes. But the advice may not pertain to YOU, as an athlete.

The bodies of athletes eagerly take up blood glucose to fuel exercise and replenish depleted muscle glycogen stores. Too few carbohydrates (wholegrains, fruits, vegetables) result in needless muscular fatigue if you train hard day after day.

That said, some very athletic people live in large bodies. They tend to be frustrated as they can’t shed fat despite religiously abiding to a restrictive diet plus rigorous exercise.  As one triathlete complained “I should be pencil thin by now, with all the exercise I do…” What’s going on? The answer might relate to that athlete’s personal insulin response to carbohydrate. Research suggests genetics causes some people to be high insulin secretors.

What does this mean for you, a weight-conscious athlete? If you struggle to lose weight, you might be a high insulin secretor. Take a look at your family genetics: Do your relatives gain weight easily? Do they have diabetes? If yes, you may consider checking your fasting blood glucose, insulin levels and HBA1c (long term measure of blood glucose). Some athletes do better on a low glycemic diet, trading processed carbs for whole grains and combining them with lean protein and healthy fats such as nuts, nut butter, and avocado.

Discussing the demands of your chosen sport and undertaking some basic pathology testing could help you work out what’s the best-balanced solution to weight management for you.

Article adapted from Nancy Clark Sports Nutritionist based in USA. 

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