• First published on July 09, 2015
Carrying excess body fat is usually disadvantageous in most sports, and players should be aware of how keeping fat low can be achieved.
Body fat can be assessed by using skinfold measures since this is easy to administer and transport, or by using DXA (Dual X-ray absorptiometry) which entails significant expense and a trip to some laboratory. There are also so-called body fat assessing devices linked to weighing scales which purport to measure body fat by electrical conductivity. I have to say that my experiences with using electrical impedance is fraught with problems – not least of which is that levels of fluid intake or dehydration have a greater effect!
Anyway, whatever device is used for body fat estimation, what kind of readings can you expect? The table below highlights what are acceptable values. As you can see, the average scores for non-active males and females are about 20% and 30% respectively. However, athletes in most sports should attempt to get closer to 10% and 15% for males and females. The professional athletes I have worked with over the years are required to be less than 10% for males and between 12-15% for females. The discrepancy between males and females is approximately 10% i.e. higher for females due to greater levels of female hormones and lower levels of testosterone.
Having said that, I really should point out that we are all different and where some individuals are naturally lean and can easily achieve or maintain low body fat scores, others have difficulty. I have dealt with many elite players whose body fats are slightly above what the team average is supposed to be and yet they perform really very well. I tell them not to get hung up about this problem as long as they perform well. Remember these are guidelines and should not be set in stone.
From a nutritional perspective, excess carbohydrate intake does lead to an increase in fat deposition. This is because the body only has a limited supply of carbohydrates (around 200-500 grams found mainly in the muscle but also the liver) and when these stores are full, the liver has the capacity to convert the excess carbohydrate to fatty acids which then get taken to the fat storage areas. Of course eating too much fatty foods or too many calories in general will also lead to an increase in fat deposits around the body.
The point about eating carbohydrates and the link with the potential to increase body fat is that when carbohydrates are digested and absorbed they increase blood glucose, which in turn stimulates the release of the hormone insulin to ‘dispose’ of the glucose. This is achieved by storing the glucose in muscle and liver, but any excess is stored as fat. So insulin is an anabolic hormone, which means it promotes storage rather than breakdown. Insulin is a potent inhibitor of fat breakdown and release, so if you need to break down fats and use them for energy don’t eat carbohydrates! Any situation which promotes insulin stops fat burning, and so any situation which reduces insulin promotes fat burning.
The last statement is important because it should be borne in mind when you train for so-called ‘fat burning’ sessions. These sessions, which are in the main, aerobic based sessions, should be undertaken without carbohydrate feedings either before or during. Put carbs into your body and you stop fat burning; keep off the carbs and you fat burn in training.
So what should you do or eat before training if the emphasis is to reduce body fat? Quite simply keep away from carbohydrates for 3-4 hours before training, and if you need to have some carbs then eat a small amount of low GI carbs. Many scientific studies have demonstrated that high GI carbs in the hours before training favours carbohydrate burning and not fat burning during the subsequent session. Of course, drinking carbohydrate sports drinks during training also stops fat burning and promotes carbohydrate burning. So, you have been warned!
Studies in my laboratory have demonstrated that ideal fat burning can be achieved in the morning after an overnight fast i.e. having nothing to eat before training for around 8-10 hours. Now this may be difficult for some individuals, especially those who do not want to lose muscle mass, so the next best thing is to have a small amount of a protein drink or food such as plain natural yoghurt or an omelette or poached eggs (but NO toast or bread). I would recommend not to eat cereal or to drink milk, as milk contains carbohydrate in the form of lactose and cereals contain various forms of carbohydrate. Remember, ‘Put carbs in your mouth and you don’t burn fat’.
The question then remains, what should you eat after training? Now here is another conundrum. After training, your metabolism is elevated for some time, and the harder or the longer the session the longer period of time your metabolism remains elevated. This can be measured in a laboratory by noting the higher levels of oxygen after exercise and so is known as EPOC or elevated post-exercise oxygen consumption. The levels of fatty acids in blood also remain high after exercise and they can be a useful fuel source in the recovery period – hence fat burning continues after exercise. If you wish to continue burning fat in the recovery period after exercise then you should try and avoid eating any carbohydrate for maybe up to an hour or two.
So what do you eat? Protein and fatty foods, or even just drink water! This means having a small snack of a cheese/plain/ham omelette or hummous/peanut butter and celery/carrot baton or a cheese/egg/tuna salad. Indeed, any foods that do not any or very little carbohydrate.
I do have a word of warning, however. This idea of keeping off carbohydrate foods is fine for burning fat but not helpful for restoring muscle carbohydrate. If you know you either have a hard session later in the day or a competition the following day, then eating or drinking carbohydrate after the session is important. As with most training and nutrition, it really is a matter of what your priorities are i.e. fat burning or recovery for the next session?
• Athletes who have a high body fat could be at a disadvantage in their sport
• Body fat percentage values reflect what an athlete needs to reach – but do not get too hung up about getting below certain norms if performance is going well
• Eating too much carbohydrates will invariably lead to an increase in body fat
• Eat carbohydrates before and/or during training and you will not burn fat
• Consider fat burn training first thing in the morning after an overnight fast
• At the very least ensure little or no carbohydrate is consumed in the hours before a fat burning session
• Fat burning continues once the session is complete, so consider keeping off carbohydrate for an hour or two afterwards
Professor Don MacLaren is part of the team who have developed Nutrition X’s range of fully tested products, which have become the No.1 choice of sports nutrition for numerous elite athletes, amateur sports people and casual gym users alike.
For more information, or to discuss your sports nutrition requirements, please contact Don MacLaren via www.nutritionx.co.uk
The information on this website is intended for entertainment purposes only and does not constitute professional, medical or healthcare advice or diagnosis, and may not be used as such.
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