Living with Diabetes

How to lose weight safely and effectively


The relationship between what you eat and exercise is a simple one. Compare yourself to the fuel tank of your car. Imagine the tank is being filled at the top. At the same time, a pipe at the bottom which leads to your engine allows the fuel to leave. Provided fuel enters and leaves at the same rate, the amount of fuel within the tank remains unchanged.

Now imagine that the fuel entering the tank represents the calories you eat. The fuel leaving the tank being used up by your car’s engine is your energy expenditure. This is the amount of calories you burn up through exercise. If you have more calories going in than going out your tank is going to 'overflow'.  The excess energy is converted into fat and will remain in your body.

I don't eat that much!

Many who are overweight don't acknowledge that they eat more than they should. Perhaps they don't. It may well be that they expend less energy than they take on board. To achieve a happy balance and to lose weight we need to diet as well as exercise. If you are not very active you should restrict your diet as the excess energy will make you gain weight.

I can’t starve!

You do not have to ‘starve’ yourself to lose weight. If you reduce your intake of food by 250-500 calories a day you would lose 1-2 pounds a week. This is a ‘sensible’ rate of weight loss to aim for.

You would lose 26 pounds or nearly two stone at the rate of one pound a week if sustained over six months!

How much exercise do I have to do?

A pound of fat represents about three and a half thousand calories of stored energy. Compare this to a gallon of petrol in your car which can take you thirty miles. If you don't drive anywhere, the gallon of petrol will stay in your tank.

If you eat 2500 calories a day and expend 2000 calories your body retains 500 calories each day. Over the course of a month you would therefore retain (30 x 500 ) 15,000 calories which as we said before is equivalent to over 4 pounds of fat, as one pound of fat is about 3,500 calories.

The following table gives you an idea of how much work you have to do to get burn off excess energy.



Exercise to ‘burn off’



Doing nothing (sleeping) you will still use this much energy in an hour

Cream Biscuit


Cycle for half hour

Bailey’s Irish Cream


Swimming for twenty minutes

Packet of Crisps


Walk for half hour

Pint of Beer


Gardening for half an hour



Brisk walk for one hour

Practical advice on losing weight

  1. Set yourself a target which is achievable. For example, if you weigh 20 stone, don't plan to get down to 10 stone because you won't. A reasonable target is around 10% of your current weight. Write down your target weight somewhere so that you remember.
  2. Aim to lose between 1-2 pounds a week. People who lose weight rapidly often put it back on rapidly.
  3. Draw up a list of foods you are going to avoid eating. You should aim to eat less fat and little or no sugar. Deserts are a no go area if you are going to have any hope of losing weight effectively as they often give you a whole day's worth of calories!
  4. Study the nutritional information on food packaging. There is often a lot of useful stuff which we disregard and throw away. This information helps you understand the relationship between food and body weight.
  5. Keep a diary of your day. How much time do you spend in sedentary activities such as sleeping, reading, watching television and mealtimes ? Could you fit in a little more exercise ?
  6. Reduce your intake of alcohol, beer in particular.
  7. Don’t snack between meals.
  8. Don’t take second helpings at meal time.

Common problems with trying to lose weight

  1. Poor motivation – weight gain is associated with low mood and feeling ‘defeated’. You may find that you lack the will power to stick to a programme of diet and exercise.
  2. Obesity results in a reduction in your ability to exercise. People who are obese suffer from fatigue, breathlessness, painful knees, poor circulation and sweating which make them unable or reluctant to exercise.
  3. Hunger is a powerful stimulus and can be difficult to overcome.
  4. Social pressures with food and drink. Keeping to a diet is especially hard if those around you are having a feast!
  5. Other factors may contribute to weight gain – eg. Stopping smoking helps you put on weight as your appetite improves.


Dr Nishan Wijenaike MD, FRCP
Consultant Physician (Diabetes and Endocrinology)
West Suffolk Hospital NHS Trust
Bury St Edmunds
August 2006