With a change in many recommended diets ? limiting carbohydrates in favour of proteins and fats ? should you be thinking about changing the balance of your diet?

In June, the International Journal of Sports Nutrition and Exercise Metabolism presented a case study which had some interesting results. Comparing the effect of a low-carbohydrate with a grain-based diet, there seem to be pros and cons to both approaches.

The evidence

The authors compared the effects of both diets on body composition, athletic training and performance markers over a 14-day period, with an endurance-trained subject following a pre-scheduled training programme. The low-carb diet consisted of 54.7 per cent fat, 21.5 per cent protein and 23.5 per cent carbohydrate. The grain-based diet consisted of 59.2 per cent carbohydrate, 12.2 per cent protein and 28.6 per cent fat.

Results showed more disruption to training and unfavourable subject experiences, such as lethargy and fogginess, with the low-carbohydrate diet. Total cholesterol, HDL, LDL, ratings of perceived exertion and heart rate were also elevated.

But measured showed that the low-carbohydrate diet may lead to less inflammation in the body and improved lactate clearance. It also led to weight loss, with 2.8kg being lost over 14 days, versus 0.6kg gained on the grain-based diet.

Layman lowdown

The study looked at somewhat extreme variations of each diet, and it may be that there is a ?happy balance?. It would seem, however, that the grain-based diet elicits more performance benefits while having a better effect on cholesterol levels. But the low-carbohydrate diet seems to have benefits in terms of a reduction of inflammation in the body, which has serious benefits for health, while also proving an effective method for weight reduction, which can indirectly benefit performance.

This study highlights the need for further examination of diet balance, ideally taking into account the quality of food as well as type, so that more meaningful conclusions can be drawn.