Great Britain’s gold medal hopes have suffered a major blow ahead of the Olympics with the news that boxer Frankie Gavin will not be competing in Beijing. The 2007 World Champion has failed to meet the required weight of 60kg (9st 6lb) to compete in the lightweight category. In order to meet the requirements he would have needed to weigh in at 60kg every day that he competed at the Olympics. Gavin, along with Russian Alexei Tischenko, had been a favourite to win gold in the lightweight division and the news of his withdrawal we be a setback to Team GB.

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Weight problems are a common occurrence in boxing and Ricky Hatton is famed for his dramatic increases in weight between fights. When a fight is announced Hatton will begin a rigorous training schedule and this involves the incorporation of a weight loss programme.

One way sports competitors lose weight is through fat burning and this is a very popular and often-used term among athletes. The term ‘fat burning’ refers to the ability to oxidise (or burn) fat, and thus to use fat – instead of carbohydrate – as a fuel. Fat burning is often associated with weight loss, decreases in body fat and increases in lean body mass, all of which can be advantageous for an athlete but often a necessity for a boxer in order to meet their weigh in.

It is known that well-trained athletes have an increased capacity to oxidise fatty acids. This enables them to use fat as a fuel when their carbohydrate stores become limited. In contrast, patients with obesity, insulin resistance and type II diabetes may have an impaired capacity to oxidise fat. As a result, fatty acids may be stored in their muscles and in other tissues. This accumulation of lipid and its metabolites in the muscle may interfere with the insulin-signaling cascade and cause insulin resistance.

There is evidence that shows that trained individuals store more intramuscular fat and use this more as a source of energy during exercise. Fat oxidation is regulated at various steps of this process. Lipolysis is affected by many factors but is mostly regulated by hormones (stimulated by catecholamines and inhibited by insulin). The transport of fatty acids is also dependent on blood supply to the adipose and muscle tissues, as well as the uptake of fatty acids into the muscle and into the mitochondria. By inhibiting mobilisation of fatty acids or the transport of these fatty acids, we can reduce fat metabolism.

Factors affecting fat oxidation:

Exercise intensity –

One of the most important factors that determine the rate of fat oxidation during exercise is the intensity. In absolute terms, carbohydrate oxidation increases proportionally with exercise intensity, whereas the rate of fat oxidation initially increases, but decreases again at higher exercise intensities. So, although it is often claimed that you have to exercise at low intensities to oxidise fat, this is not necessarily true.

Diet-

A diet high in carbohydrate will suppress fat oxidation, and a diet low in carbohydrate will result in high fat oxidation rates. Ingesting carbohydrate in the hours before exercise will raise insulin and subsequently suppress fat oxidation by up to 35% or thereabouts. This effect of insulin on fat oxidation may last as long as six to eight hours after a meal, and this means that the highest fat oxidation rates can be achieved after an overnight fast.

Duration of exercise-

It has long been established that oxidation becomes increasingly important as exercise progresses. During ultra-endurance exercise, fat oxidation can reach peaks of 1 gram per minute, although (as noted in Dietary effects) fat oxidation may be reduced if carbohydrate is ingested before or during exercise. In terms of weight loss, the duration of exercise may be one of the key factors as it is also the most effective way to increase energy expenditure.

Nutrition-

There are many nutrition supplements on the market that claim to increase fat oxidation. These supplements include caffeine, carnitine, hydroxycitric acid (HCA), chromium, conjugated linoleic acid (CLA), guarana, citrus aurantium, Asian ginseng, cayenne pepper, coleus forskholii, glucomannan, green tea, psyllium and pyruvate. With few exceptions, there is little evidence that these supplements, which are marketed as fat burners, actually increase fat oxidation during exercise.

One of the few exceptions however may be green tea extracts. We recently found that green tea extracts increased fat oxidation during exercise by about 20%. The mechanisms of this are not well understood but it is likely that the active ingredient in green tea, called epigallocatechin gallate (EGCG – a powerful polyphenol with antioxidant properties) inhibits the enzyme catechol O-methyltransferase (COMT), which is responsible for the breakdown of noradrenaline. This in turn may result in higher concentrations of noradrenaline and stimulation of lipolysis, making more fatty acids available for oxidation.

Frankie Gavin will have a career changing decision to make following his Olympic disappointment. He will have to choose between the lucrative option of turning professional or remaining amateur and waiting until the 2012 London Olympics to realise his Olympic dream. Whichever path he chooses Frankie Gavin is going to need a training method that keeps his weight down.

At present, the only proven way for him to increase fat oxidation during exercise is to perform regular physical activity. Learn how to apply new exercises to your programme and increase your fat oxidation by subscribing to Peak Performance.

Related links:

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