I’m going to talk here about the results of two studies. The first study says that they have conclusively proven that if you exercise at a higher intensity, you will lose more fat. And really, this probably sounds like the most obvious thing ever, right?! But it’s interesting because for years most exercise physiologists have actually believed, and I’m not making this up, that exercising at medium intensity is the best way to lose fat, eg, long slow walks.

There was some graph developed years ago based on some study and I don’t remember how but it came up with that conclusion but it did, I still remember getting taught it in my Sports Science degree. I didn’t really understand in then, and I still don’t now.

But I don’t want to bad mouth moderate intensity. You can exercise for a longer period at a moderate intensity than you can at a higher intensity, and so over time in a moderate intensity session you can get a great effect. Absolutely. And high intensity is not for everyone. I always advocate a gradual return to exercise if you “haven’t been doing much lately”, or a gradual increase if you are currently exercising – stepping it up or introducing a new activity are prime times for injury.

And it’s important to have balance – mentally it is hard to exercise at a higher intensity all the time and physically it’s near impossible – all the elite athletes I have worked with have a combination of hard sessions and easier sessions in their schedules.

And so, yes, you will burn some fat by doing medium intensity exercise, it’s a fuel after all, and you’ll need some fuel to get yourself around, but this study showed that for obese middle aged women (and it would be reasonable to think that this would apply to other people), high intensity exercise training generated significant reductions in abdominal fat levels (which are a key indicator in predicting risk of heart attack http://tinyurl.com/9w4f84), whereas no exercise or low intensity training produced no significant results.

Other studies have shown it’s not enough to just diet http://tinyurl.com/8evpfb, in short, you’ve got to work it off people.

If you want results you’ll have to get out there and work hard for them. Even short bursts of intense exercise can increase metabolism http://www.medicalnewstoday.com/articles/136910.php

The second study looked at whether what you eat prior to exercise affects how you burn fat. There are plenty of theories around regarding how to get the best performance out of your workouts, and plenty of research has been done on elite athletes. In this study, researchers examined whether eating Low GI or High GI foods prior to exercising had any effect on the amount of fat burned in normal, everyday, garden variety women, who they call “sedentary”.

They only used a small number of women in this study (8) but the trend is interesting, and it supports a) previous research done on other people, and b) what they expected to find. The women were given Low GI (GI 44) or High GI (GI 78) breakfasts 3hours prior to being asked to walk for 60 minutes. They were then given the same lunch 2 hours after exercising.

The Low GI group oxidised more fat during exercise. What this means is that after eating a Low GI breakfast people will burn fat preferentially over other types of fuels in the body, that is, you will shed fat before you shed muscle or muscle glycogen.

Another interesting finding was that the Low GI breakfast group, who then went on to eat the same lunch as the High GI group, reported that they felt fuller following lunch. This is an interesting flow on effect which may help those trying to lose fat – not only do you burn more when exercising, you may also later feel the need to eat less.

For a list of Low GI foods go to http://www.the-gi-diet.org/lowgifoods/