Cook yourself steak and eggs before going to the gym — it could help you to lose more body fat, American researchers suggest.

For many years, pasta, energy bars and other high-carbohydrate foods have been the dietary staples of those looking for an immediate and long-lasting energy boost before exercise.

But a new study suggests that a protein-rich diet could help exercisers to get more out of their programme. Researchers at the University of Illinois department of nutrition science have discovered that such a diet “enhances the effectiveness of an exercise regimen” far better than the so-called “carbo-loading” usually favoured by those trying to get fitter. In the study of 48 women, published in the Journal of Nutrition, Professor Donald Layman and his colleagues found that those who replaced complex carbohydrate foods such as pasta, rice and wholemeal bread with high-protein foods such as dairy products and meat lost more body fat and had greater improvement in muscle tone.

For four months, the female subjects who took part were assigned either a high-protein or high-carbohydrate eating plan providing about 1,700 calories a day. In addition, the women were asked to follow one of two fitness programmes; either walking 30 minutes a day, five days a week, or walking the equivalent of 30 minutes every day and completing two weights sessions at the gym. Although all the women who followed the second, more demanding, workout schedule lost the same amount of weight, for those on the protein-rich diet the losses were almost totally from body fat.

In the carbohydrate group, however, one third of the weight lost came from muscle. “There’s an interactive effect when a protein-rich diet is combined with exercise and the two work together to correct body composition,” says Professor Layman. “Dieters lose more weight and they lose fat, not muscle, which is important.” The high-protein diet provided the exercisers with high levels of the essential amino acid leucine. Together with insulin, leucine stimulates protein synthesis in muscles, which keeps them strong and toned while allowing the body to burn fat.

To obtain what Layman refers to as “the metabolic advantage” of a high-protein diet, he recommends that exercisers add dairy, meat and eggs to their daily food intake while cutting down on carbohydrates, although not eliminating them completely. Healthy eating guidelines “do not provide enough leucine for adults to maintain healthy muscle”, he says. On average, a typical Western diet contains four to five grammes of leucine but “to get the effects we are seeing you would need to get nine to ten grammes a day”. The England rugby team adopted a higher protein and lower carbohydrate diet in the run-up to their victory in the 2003 Rugby World Cup. Although criticised at the time, it seems that the nutritional approach may well have contributed to the fitness levels that led to their success.

So does this signal a return to the footballers’ steak-and-egg diet of the 1970s? Jeanette Crosland, a consultant dietitian to the British Olympic Association, says that while dietary protein is known to be required to enhance the recovery of muscles after intense exercise, it should not be increased too greatly at the expense of all carbohydrate for people playing sport. “A high-carbohydrate snack along with some protein is particularly useful as an immediate pre-workout meal, ” Crosland says. But the type of carbohydrate consumed can also be influential. In two studies published recently in the International Journal of Sports Nutrition, Dr Emma Stevenson, a researcher at the University of Nottingham school of biomedical sciences, looked at how the glycemic index of a pre-workout meal affects performance.

Dr Stevenson gave athletes either a high-GI breakfast of cornflakes and milk, white bread with jam and a sports drink, or a low GI meal of muesli and milk, tinned peaches, an apple, a yoghurt and apple juice and asked them to carry out a 60-minute run three hours later. She found that the low-GI, pre-exercise meal was more beneficial in terms of improving performance.

“It promoted fat oxidation, sparing carbohydrate for use later in the run, which led to a significantly better performance.” Other studies have shown similar results. One, published in the International Journal of Sports Medicine a few years ago, found that elite cyclists who ate low-GI lentils an hour before exercise were able to keep going an average 20 minutes longer than those who ate high-GI mashed potato.

“There is plenty of evidence that eating a low-GI meal one hour before exercise can be helpful, but we have now shown that a three-hour gap offers improvements too, which means that if people eat a substantial breakfast or lunch they are set up to exercise at lunchtime or on the way home from work,” Dr Stevenson says. “It results in higher fat metabolism” — which means it will help you to lose weight as you get fit.

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