1 March 2010

Body Work with Glenn Cardwell

‘When should I exercise? I have read that you will burn more fat if you exercise before breakfast.’

Glenn Cardwell
Glenn Cardwell

‘The biggest factor for burning body fat is whether you do the activity in the first place. It may be interesting to speculate whether you burn more fat in certain circumstances, but the best I can give you is a general guide.

  1. To burn fat you have to be active in the first place.
  2. The fitter you are the better your body is at burning fat. To get to a reasonable level of fitness, you need to move your body 3–5 times a week.
  3. It doesn’t matter if you walk or jog. You will burn more fat jogging for 30 minutes than walking for 30 minutes. On the other hand, you will burn more fat by walking for 60 minutes than jogging for 30 minutes.
  4. The amount of incidental activity during the day will potentially burn more fat than a jog. Getting up from your chair, having a stretch, taking a quick walk around the office, using the stairs etc will probably burn more body fat during the day. So don’t do 30 minutes of exercise then tick the exercise box and plonk your bum on a chair for the rest of the day.
  5. Notice how fidgeters tend to be leaner? One study showed that fidgeters burned an extra 40–60 Cals (165–250 kJs) an hour. Regularly have a wriggle in your chair or a fidget while you stand.
  6. Weight bearing exercise like walking, aerobics and jogging are better at burning up fat stores than weight supported exercise like swimming or cycling. However it’s better to do something you enjoy than analyse its fat burning potential. Refer back to point 1.’


Anonymous said...


I'm not sure that the original question was answered. Taking all of your points into consideration, the question remains -- is it more beneficial to eat your breakfast before a workout or after?

I walk every day to work and this takes about 45 minutes, and I then eat breakfast. I had heard that it was better to have my breakfast after the walk (I guess for fat burning reasons). However, here the newsletter states that the later you postpone your breakfast, the greater the effect on blood sugar issues/insulin.

So, do you recommend eating a breakfast before or after exercise, when this exercise is almost first thing in the morning? I'm not thinking just in terms of fat burning; more in terms of overall health (and the impact on blood sugar).


GI Group said...

We have passed your comments on to Glenn and he will answer them as soon as possible.

GI Group said...

Glenn says: "The point I didn't make particularly well was that it probably didn't matter whether you exercise before breakfast or after breakfast if you are trying to lose body fat. The same applies, I believe, for overall health. I walk the dog in the morning for 45 to 60 minutes and then come home and have breakfast. Sometimes in the winter I wake up and it's raining so I might have breakfast, wait for the rain to clear, and then walk the dog. I think my health benefits from either option. It is the combination of being active and eating well that has more influence on your health than the order in which you eat and exercise.

I think the point being made in the breakfast article was that it wasn't smart to a) delay breakfast for many hours after arising and b) consume a high GI breakfast. Eating a low GI breakfast within a couple of hours of getting up will help keep blood sugar levels normal."

tingting said...
This comment has been removed by a blog administrator.
Anonymous said...

Thanks very much for your reply!

Pascal said...

Your article mentioned people who fidget being leaner and that we should get up from our chairs and move often. I have an office job in front of a computer most of the day and Type 2 Diabetes so I need to exercise. A few months ago I switched from sitting to having a standup desk, so most of the day now I stand in front of the computer and only sit down for a short time at lunch. It has certainly stopped neck and shoulder aches from hunching at the desk but I also think it makes me move more often in that I move from foot to foot and turn around to talk to people when they come into my office and talk to them standing up rather than just swivelling on a chair. I think it has added some extra exercise and movement to my day. What do you think?

GI Group said...

Standing perfectly still burns up about 10% more kilojoules than sitting perfectly still. Once you stand up and move around a little bit, as you are doing at work, you burn up nearly double the kilojoules compared to sitting in a chair. You can even get a treadmill that will fit under your desk so that you can walk at 1.5km an hour while you work helping you to burn an extra 400kJ every hour. Well, at least they are available in the US.

Calista said...


For the last 4 weeks I have cycled as my main form of exercise averaging 15-20km/day. I am far from fit and on the high side of being obese so I am the slowest thing on the road.

From a weightloss point of view would it be more effective for me to walk an hour, or cycle for 2 hours?

Anonymous said...

Do you only answer a limited number of questions or was my question not acceptable for some reason?

calista said...

Sorry that last question was from me (Calista). Obviously I haven't got the hang of this system.

GI Group said...

We did forward this to Glenn and haven't had a reply yet. will prompt him.

GI Group said...

Hi Calista, Here are some comments from Glenn in answer to you question.

'Any exercise will help weight loss. I would suggest having a mix of exercise for variety and interest, including some upper body exercise such as swimming or weight training. It is difficult to say whether walking for an hour will burn more kilojoules than cycling for two hours. As they say, it all depends. That is, it depends on whether you are going uphill or on the flat, whether there is a head wind or tail wind. As you get fitter, you will go faster and probably burn more kilojoules. I suggest you keep both cycling and walking in your exercise repertoire. It may also be worth consulting an exercise physiologist'

Calista said...

Thanks Glen. I think I might start biking to places like the wetlands where I can walk and thus get a double benefit. I'm thinking of taking up Nordic walking which may help with the upperbody exercise.