Everyone wants to burn fatter for weight loss, body shaping, health and wellbeing or for sporting purposes. Trim that butt, waste that cellulite, smooth those love handles, bust that belly its all part of the trim and slim exercise and diet activity many of us indulge in.

The body normally burns a mix of carbohydrate, as glucose, and fat for fuel. The amount is depending on physical activity and the feeding. If anyone uses more energy than take it in from food and drink, the body burns stored fat and carbohydrates, and then even protein, to fuel ones everyday activities even if they are not exercising. When people starve of course the body starts to eat itself. It depends on the family history, genetics, feeding procedure and exercise to create the energy deficit and the body may decide to get conservative and drop the metabolic rate to try to hold onto body weight.

Some of us seem to have inherited this tendency more than others, the origins of which may be in the early periods of human evolution where 'feast or famine' was more or less the norm. Even so, starvation always works eventually and the body starts to break down its own tissue for fuel. Stored carbohydrate called glycogen is quickly used up and then goes the fat stored under the skin and around the internal organs. Protein in muscle is then broken down to create glucose to keep the brain working and conscious.

Fat and glucose are the body's two main energy sources. Glucose comes mainly from carbohydrate foods like rice and bread and potatoes and protein is supplied mainly by meat and beans and dairy products. The amino acid building blocks of protein foods can be converted to glucose in emergencies. The body always burns a mix of fat and glucose except at very high intensities, and the ratio of the fat and glucose in 'the burn' varies with intensity and time of exercise.

Weight training is increasingly recommended as a fat-busting tool because some experts say extra muscle burns more energy than body fat at rest, so if one develops more muscle and have a higher muscle to fat ratio than before, one must burn extra energy and more stored fat as a result. This is true and has been shown in metabolic studies. However, the differences are not that dramatic; perhaps less than a few tens of calories per day for each pound of muscle increased, for most people.