Being overweight can be seen as a signal to pay attention. We can easily gain a few pounds with no long-term significance. In fact, a slightly raised fat store prompts oestrogen production which is protective against certain diseases and enhances libido.

However, health risks such as varicose veins and joint problems gradually increase with a gain in body weight.

Being overweight is amongst the most common preventable health problems.

We all realise when we are putting on pounds.  Clothes dont fit anymore, you move a notch further down the belt, you feel lethargic and become breathless after little exertion.  You may feel unattractive, have a low self-esteem, and suffer excessive sweating, joint pain, and poor-quality sleep.

Definition of overweight

Being overweight means having a BMI between 25 and 29.9 kg/m².  Your energy balance has swung into a positive state and expenditure must be addressed.

Besides BMI, a waistline measurement of more than 94 cm (37 inches) for men and more than 80 cm (31.5 inches) for women suggests the need to lose weight.

The cause of weight gain

In many cases, being overweight will have occurred due to over-consumption of energy-dense foods coupled with a lack of physical activity. 

But it is not always this straightforward and we cannot assume that everyone who is overweight overeats.  A catalogue of interacting social, psychological, and metabolic factors also needs to be considered.

Lifestyle, genetics, menopause, hormonal disorders, certain medication and fluid retention due to food intolerance, stress and tiredness can all lead to weight gain.  Ageing encompasses more of these risk factors and can be seen as one in its own right.

Age

With advancing years comes an ever-expanding waistline, the rule of thumb being an increase of 1 pound per year.  The main reason is decreased energy requirements whilst maintaining energy intake.

Our Basal Metabolic Rate decreases with age, as a proportion of lean muscle tissue is replaced with fat.  However, energy intake is not usually decreased to compensate. In fact it may even increase through eating out more and socialising. 

To compound matters, less physical activity is taken as we move past 40 and 50 years old, with sport being replaced with visiting friends and shopping.

Stress and tiredness can precipitate weight gain, mainly as fluid retention due to the increased production of the anti-diuretic hormone (ADH).  Juggling a career, family and caring often increases the levels of stress and tiredness, promoting weight gain. Increased stress can also stimulate comfort eating.

With advancing age comes a cycle of change and a greater likelihood of medication use and certain diseases that lead to weight gain.  The menopause, both male and female, can aggravate matters, as can hormone replacement therapy.  There is a greater likelihood of diabetes and hypothyroidism as we get older, conditions that precipitate changes in weight.

Lifestyle

When excess calories are consumed, energy is stored as fat.  The increase in weight will, however, be due to both lean tissue and fat being deposited.

A diet that is high in fat, sugar and alcohol and relatively low in complex carbohydrates and fruits and vegetables will increase the chances of weight gain.  Fatty foods are energy dense and palatable, but not the most satisfying in terms of bulk.  With relative ease and little energy cost to the body, fats are broken down to fatty acids then rebuilt and stored as fat.  Other food components, such as protein, cost much more energy to digest and rebuild, increasing energy expenditure.

Excess carbohydrates are converted to fat in the body and stored.  The carbohydrate roller coaster can precipitate weight gain, as rapid drops in glucose levels after a period of fasting stimulate the desire to eat, when, in fact, our energy stores are more than full and we do not need to do so.

A sedentary lifestyle predisposes to weight gain, as less energy is expended and there is little development of metabolically active muscles.  A vicious circle can be established as the more overweight you become the more difficult it is to exercise.

Genetics  true and sociocultural factors

Our genes may predispose us to being overweight, playing a part in determining body weight and shape.  Genes do not make this inevitable, however, can still control our weight.

The inherited influence is twofold: true genetics, and sociocultural factors passed down through generations. 

The effects of true genetics are mainly on appetite control, the ob gene being responsible for the manufacture of leptin, one of the most recently researched genetic factors.

Family background, how we have been brought up, and our learned habits with regard to food intake and physical activity all help determine our likely adult body weight.

Childhood obesity

During the first years of life fat cells are rapidly produced.  Over-consumption during early years results in excess fat cells being made and increases the likelihood of being overweight or obese in later life.  A corpulent child may have three times more fat cells than a child of normal weight.

Menopause and andropause

Weight gain at the time of the menopause, both male and female, occurs due to a number of factors, some unknown, some because of changes in lifestyle in reaction to the menopause and to oestrogen dominance.  Temporary oestrogen dominance in women inhibits the action of thyroxine, leading to hypothyroidism.  This becomes common in later life, with 30% women experiencing it after the menopause.

Hormonal imbalance - hypothyroidism

Hypothyroidism (underactive thyroid gland) results in less production of the hormone thyroxine.  As thyroxine promotes the use of carbohydrate to supply energy and cell metabolism, an insufficiency results in a drop in energy levels; fewer calories are burned off, resulting in weight gain.

There are other hormonal disorders that promote weight gain such as Cushings Syndrome and Hashimotos Thyroiditis, but they are uncommon and the gain is usually minor.

Diabetes

There is a close association between being overweight and diabetes.  Most type II diabetics are close to obesity.

Diabetics are resistant or insensitive to the effects of insulin, resulting in poor glucose metabolism.  As a result, circulating levels of the hormone are high as more is released to try and cope with glucose intake from the diet.

Besides insulin enabling glucose uptake in the body, it stimulates fat cells to synthesise and store fat.  Hence high circulating levels of insulin associated with diabetes result in increased fat synthesis and weight gain.

Medicines and illness

Certain medicines including anti-depressants such as Monoamine oxidase inhibitors, steroids for asthma and arthritis, and anti-diabetic drugs induce weight gain.  Weight gain will be listed as a possible side effect on the medication leaflets.

Reduced mobility through illness such as arthritis or through injury can result in this too due to reduction in physical activity and the wasting of lean muscle tissue, which slows the efficiency of burning calories.

Cessation of smoking

As nicotine increases the Basal Metabolic Rate (BMR), withdrawal from the drug will automatically result in a drop in BMR, decreasing the need for energy intake.  But as many smokers who quit will know, rather than decrease food intake to compensate, energy intake tends to increase as people seek to replace the stimulant with food or alcohol.

The benefits of stopping smoking far outweigh the risk of increased weight due to its cessation.

Water retention

Water retention in the body causes an increase in weight.  Temporary fluctuations in weight occur naturally throughout the day, after meals and during the menstrual cycle, but there are times when water retention is caused by a condition that needs to be addressed.

Food intolerance, food allergies, a high-salt diet, stress and fatigue can all lead to water retention.

People with food intolerances and allergies can carry an extra stone in weight as their bodies struggle to metabolise food to which they are adverse.  A high-salt diet will increase salt levels in the blood, initiating the control mechanism to retain more water to dilute and balance the salt concentration.

Finally, stress and fatigue increase the production of the anti-diuretic hormone (ADH) from the pituitary. ADH reduces the volume of urine excreted, so retaining more fluid in the body, resulting in weight gain.

20/05/2009