Causes of weight gain

If you have discovered that you are gaining weight and don't know why, the following information may be of some assistance. Weight control doesn't just come down to what you eat and how much you exercise. There are many other contributing factors to weight gain which can be classified into three main categories. These are:

A). Energy Intake: The most common reason for weight gain relating to energy intake is excess fat intake. Fat yields 9 cals/g compared to 4 cals/g for both carbohydrate and protein. Even when fat intake is being controlled some people still gain weight and wonder why. It may be because they are still consuming too much energy through carbohydrates and/or protein. They just need to reduce their portion size.

Energy density also plays a part in weight gain because it contributes excess kilojoules. High energy dense foods are high in sugar and fat. Low energy dense foods are high in water and fibre. Even if a food is low in fat, it can be high in energy density due to high levels of sugar and low levels of water and fibre.

Other contributing factors could relate to eating habits such as night eating, social eating and habitual eating. Habitual eating may be in the form of eating chocolate and cakes when depressed or getting up to get something to eat every time an ad comes on the television.

Eating food while drinking alcohol also contributes to weight gain. Although alcohol itself is not fattening, the foods eaten with it often are. The body burns up the energy from alcohol before any other calories, so the fat consumed in these fatty foods is stored in adipose tissue.

Many people also often underestimate the amount and type of foods they eat. They may think that they only over-eat on exceptional days, but for most people, every day is an exception.

B). Energy Expenditure: Many people consume more energy than they expend, resulting in a positive energy balance and thus, weight gain. Many energy expenditure problems arise from the fact that many of us now work in sedentary jobs, and use sedentary transport methods. We may drive to work or sit on the train, instead of walking or cycling to work (this is also due to urban sprawl), and then arrive at work to spend the whole day at a desk in front of a computer.

Lack of movement (both planned and incidental) can also be viewed as a possible cause of weight gain. Planned movement may be a walk in the park, a gym lesson, or other exercise and lack of this type of activity is often attributed to 'lack of time'. Incidental movement (that which can now be done by machines) is also a problem. In an age of remote controls, elevators, e-mail and other effort saving devices, the need to move around has been educed.
Previous experience with exercise can also put people off. Exercise may remind them of torturous physical education lessons where they always failed. Thus people do not think that exercise can be fun.

C). Other Factors: Another factor that may lead to weight gain is a slow metabolism. Metabolism may be affected early in life by dieting and inactivity, and this can lead to problems later in life. Yo-Yo dieting throughout life can also change metabolism as well as fat cells, which may make lifetime weight loss a problem. However, some of these alleged problems may simply be due to a loss of "lean mass" (especially muscle) through dieting without exercise. This means a loss of tissue which burns calories, making it harder to achieve energy (calorie) balance.

Genetic problems may be another factor leading to weight gain. Weight problems do run in families, but there may also be other environmental factors contributing to the problem. Age and sex may also contribute to weight gain because body fat levels are naturally higher in women than in men, and fat levels generally increase with age. Lifestyle changes also affect weight in an indirect manner as does early experience in life such as physical or sexual abuse which may lead to weight problems later in life.

References
Factors Leading to Weight Gain, Choice Health Reader, p10-11.
Egger, G. (1999) Causes of weight gain. Waist Watch: Vol 19.

Last Updated: December 2003