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Understanding weight loss

Busy lifestyles often make it difficult to maintain a healthy weight. Weight loss pills and fad diets seem to offer a quick fix but research shows that 95 per cent of dieters regain the weight they lost within one to five years.

The weight loss industry is worth billions of pounds yet obesity is increasing at a dramatic rate. According to a study published earlier this year, 67 per cent of men and 57 per cent of women in the UK are overweight or obese.

Being overweight increases the risk of a range of conditions including type 2 diabetes, high blood pressure, coronary heart disease and certain cancers.

At first glance, the mechanisms of weight loss are simple. In order to lose weight a person must consume fewer calories than they use. In other words, eat less and be more active.

Unfortunately, this is easier said than done. A hectic schedule, bad habits and a lack of knowledge often lead to failure. In addition, we must take into account the quality of our food. The low fat diet that was once promoted as the universal answer to weight loss has become discredited in recent years. Sugar, not fat, is now generally considered to be the main culprit behind our expanding waistlines.

Understanding the science behind weight loss is the key to implementing effective strategies to help you achieve your weight loss goals.

Weight vs body fat

We live in a society obsessed with weight but is it really a valuable measure of how healthy we are? Our bodies comprise a large number of tissues but when we step onto the scales we are presented with a single value for mass that takes no account of body composition.

Those who exercise will lose body fat and gain muscle. As muscle is more dense than fat, their weight may remain the same or even increase. Conversely those who appear slim may have little muscle mass and a high percentage of body fat.

Measuring body composition is a far more accurate means of charting progress than weighing ourselves. This can be done in several ways. Taking skinfold measurements with callipers at specific sites on the body is one of most common ways to measure body fat. Unfortunately, this is impossible to perform on oneself. There are, however, an increasing number of scales on the market which measure body composition as well as weight.

Additionally, waist to hip ratios and simple girth measurements can give a useful indication of fat loss. As fat stores decrease, the circumference of body parts such as the waist or thigh, also decreases.

Women store more body fat than men, usually in the thighs, hips, bust and back of arms. Men tend store fat in the abdomen. The average body fat percentage for healthy men is between 10 and 15 per cent. The figure for women is 18 to 25 per cent.

Reducing body fat

In order to lose fat we must eat less and increase our energy expenditure. The best way to do this is by a combination of healthy eating and exercise. Although weight may barely change in the initial phases of the programme, it will decrease once the amount of lean body mass has reached a stable level.

Dieting alone can have negative long-term effects. Although the initial weight loss may be high, much of this will be due largely to loss of water and muscle. Muscle loss in itself is unhealthy as it impairs our ability to perform everyday functions, particularly as we get older.

It also slows down our metabolism so when the dieter returns to normal eating their body burns fewer calories and they put on weight more quickly. This explains why so many dieters regain the weight they lost and accounts for the phenomenon of yo-yo dieting.

Not all calories are equal

While reducing calorie intake is fundamental to weight loss, we should also consider the quality of the calories we consume. Choosing the correct foods can greatly assist weight loss while poor choices such as junk food will lead to weight gain.

In general, you should focus on high-quality, unrefined and minimally-processed foods such as vegetables, whole grains, healthy fats and lean protein. Avoid processed and refined foods, sugar, fried foods and those which contain trans fats.

Understanding metabolism

There are three main elements to metabolism:

Basal Metabolic rate

This is the rate at which the body works at rest and accounts for 70 per cent of our total daily energy/calorie expenditure.


This includes daily activities and structured bouts of exercise and accounts for 15 per cent of energy expenditure.


The thermic effect of digesting food accounts for 15 per cent of calorific expenditure.

Factors affecting metabolic rate include the amount of lean body mass (active muscle), which can be increased by resistance training, and cardiovascular fitness, which can be increased by cardio activities.

Exercising for fat loss

As we have seen, the more active muscle we have, the faster our resting metabolism. It is therefore essential to include some kind of resistance training in any fitness programme in order to increase muscle mass.

Aerobic activity is also key as it burns calories and improves cardiovascular fitness. High intensity work such as interval training has gained popularity in the last couple of years and deservedly so. As well as burning calories during the exercise session, our bodies continue to burn calories for several hours afterwards in order to restore oxygen supplies depleted during the workout.

However, someone who is obese or seriously overweight may have difficulty performing high intensity work. Instead, it is recommended they perform long duration, low to moderate intensity activity. They can incorporate higher intensity work into their programme as fitness level improves. If you are training at a high intensity, you should aim for 20 to 30 minutes. When choosing a low intensity workout you should train for longer, ideally at least 45 minutes to an hour.

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