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21 Jan 2009

I am a 32 year old female. What is the equivalent of 400cKal? I do 50 minutes of cardio and then burn about 400cKal. But I am not sure if this is enough exercise per day?

Also I would like to know what my 60-80% heart rate must be in order to burn fat. How do I work out my max heart rate? I weigh 54.8kg.

If I do 1 day cardio only and 2 days weight training, will I loose weight?
Answer 737 views

01 Jan 0001

Hi there

A kCal is a unit of energy, which is equal to 4.18 kJ (it's kind of like comparing miles to kilometers). I'm not sure what you mean by the "equivalent", but 400kCal is a pretty normal amount to be burning during exercise. To give you a comparison, a cyclist in the Tour de France will ride for 6 hours and burn close to 6000 Calories! But that's extreme - most people will burn about this much.

The key, however, is to avoid getting stuck on numbers and trying to manage weight loss this way. The most basic way of looking at calories and weight loss is to say that to lose weight, you need to eat fewer calories than you burn. You put calories in by eating and you burn them by exercise, and by just going about daily living. Now, to lose weight, you need to address both sides of this equation. In otherwords, you must both increase what you burn (by means of exercise) and you must decrease what you consume. However, the reality is probably not quite as simple as this. Hi there

There is no answer to this one, because it depends completely on the person, their situation and their diet. Let's say your diet gives you 2000Cal per day. During 24 hours, you might burn about 1600 Cal WITHOUT exercise. That would mean 400 need to be burned during exercise, in order to reach perfect balance. This is the idea in theory, but there are 3 reasons why it just doesn't work to think like this, and only causes problems.

First of all, it's impossible to know exactly how many calories you take in. You would have to weigh all your food, and that is a nightmare to do. You would have to sit and weigh each part of your meal, know exactly what you eat and drink and then sit with a calculator and work out how many calories you've taken it.

Secondly, it is even more impossible to know how many calories you have burned during the day. Even during exercise, it's not possible to measure with 100% accuracy how many calories you have burned, because the heart rate monitors and machines are just guesses or estimates. And that's not even talking about the other 23 hours a day, where you burn far more calories. So this makes it impossible.

And lastly, it really doesn't work as simply as this anyway. The body is so well created that it can match intake to use over many many years. If you think about it, someone who remains at a stable weight over a period of just 10 years, is probably eating an average of 8 or 9 million calories during this period. In order to remain at the same weight, the body is somehow balancing this amount by using about 8 or 9 million calories too! So, it’s staggering that the body is able to do this as efficiently as this, and for this reason, being very particular about counting calories all the time is probably a lost cause. It’s also the reason why sudden crash diets, where you cut right back on eating and live on lettuce every day, for example, will not work. The body simply adjusts its metabolism and so you use fewer calories. This also promotes weight gain when you do eventually start eating again.

So, rather than taking drastic steps, you have to realize that slow and steady progress is the key. It is a useful idea to become educated about what you are putting into your body, and then to be sure that it’s not excessive. The general recommendation is that for a sedentary, inactive person, you should aim for about 29 calories per kilogram (A 70 kg person, for example, would need about 2000 Cal per day). If you check out your diet, and read up how much you are putting in, and it’s around 2500 or even 3000, then you will never lose weight (or you would have to exercise like a demon, which is probably not an option). It’s also not a good idea to be consuming way under 2000 Cal per day, because this will cause the body to slow its metabolism down, as I mentioned earlier.

So, the key is to cut down on those calories very slightly (and this is simple enough to do if you take practical steps – slightly smaller portions, less variety, eat foods like apples and citrus fruits that are high in fibre etc.), and to increase your energy expenditure by means of exercise. Just 30 to 45 minutes, 4 or 5 times a week is enough to increase your overall energy expenditure by a large amount. For example, 30 minutes of walking burns about 300 Cal, and the effects last longer than just the actual exercise time. Therefore, if you are inactive now, and you suddenly start exercise by walking 30 minutes, you will be using 300 Cal more than you were previously. At the most simple, this means that if you diet stays the same, you will lose weight.

I hope that this has helped a little – I have tried to just give you a general idea. For a specific diet and eating plan, a dietician is far more qualified than I am to advise you, and I would suggest getting in contact with one to discuss this.

Good luck
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