How can I tell if I am obese?

This question may sound redundant, but many people do not in fact realise they are overweight or obese. Doctors use a measure called the body mass index (BMI) to find out if someone is underweight, normal, overweight or obese. At its simplest, BMI is a general guide to determining whether an individual is a healthy weight for their height.

BMI is calculated by dividing a person's weight in kilos by the square of their height in metres.

• A BMI of less than 18.5 is considered underweight
• A BMI of 18.5-25 is considered normal
• A BMI of 25-30 is considered overweight
• A BMI of 30 or higher is considered obese

To work out your BMI the easy way, use this online BMI calculator.

BMI doesn't apply to everyone ⁽¹⁾, however, and should not be used to assess children, pregnant or breast-feeding women, athletes and people who train with weights, the over-60s and people with certain long-term health conditions.

How do people get obese?

Weight gain due to increased body fat is normally caused by eating more calories than the body needs. The UK Department of Health recommends a healthy, balanced diet, with an average daily calorie intake of about 2,000 for women and 2,500 for men ⁽²⁾.

There are many factors that affect how many calories each person needs, including levels of activity, age, gender, height, weight, build and metabolic rate.

The metabolic rate is how quickly you burn off calories from food and drink. This varies from person to person and speeds up when you are growing and developing, before levelling out as an adult.

Those with a slower metabolism will be more prone to weight gain unless they control their calorie intake and maintain a reasonably active lifestyle. Increasing levels of activity through regular exercise not only burns calories but can also help raise your metabolic rate and prevent obesity.

Active people will usually have a higher metabolic rate than those who are inactive. This means that they burn any excess calories rather than storing them as fat.

For example, an athlete or someone with a physically demanding job could eat and drink up to 5,000 calories a day and still maintain a healthy weight. An inactive office worker who commutes to work by car may have to limit themselves to 1,500 calories a day to avoid putting on weight.

The body's natural reaction is to store fat to protect itself from starvation. But with starvation being virtually non-existent in developed countries where there are plentiful supplies of food and drink, obesity has become increasingly common. The national appetite for fast food and snacks that are high in fat and sugar, together with falling activity levels, has made the situation worse.

What are the effects of obesity on health?

There are serious health implications associated with being obese and the condition is known to shorten life expectancy.

Those with a body mass index (BMI) of 30 or more have a very real risk of:

High blood pressure

People who are obese are twice as likely to have it as people who are a healthy weight

High blood cholesterol

Obese people are more likely to have high levels of "bad" cholesterol in their blood, particularly if fat is stored around the waist or abdomen

Cancer

There is evidence to suggest that being obese can increase the risk of developing certain cancers ⁽³⁾

Gallstones

Obesity increases the likelihood of your developing gallstones

Heart attack

The health of a person's heart is directly linked to body fat and obese people are more susceptible to heart disease and heart attacks

Gout

Being overweight or obese increases the chances of developing this painful condition

Stroke

Obesity is a major risk factor, particularly if fat is stored around the waist

Infertility

Obesity is recognised as a contributory factor in infertility

Type 2 diabetes

Obesity (and increased waist size in particular) significantly increases the chances of developing Type 2 diabetes

Depression

Obesity is commonly associated with low self-esteem and depression

Eating disorders

Eating an abnormally large amount of food is sometimes part of an eating disorder which may be related to psychological issues

Low sex drive

Obese people can experience problems with energy levels, sexual desire and performance

Arthritis

If you are obese then your joints are supporting much more weight than they should. It is therefore more likely that you will develop arthritis, particularly of the knees, hips and back

How can I help myself?

• Eat a healthy and balanced diet, including plenty of fruit and vegetables, starchy foods (pasta, rice and wholemeal bread), protein-rich foods (fish, lean meat and eggs) and some dairy products
• Cut back on sugar. Reduce your intake of foods containing added sugar (cakes, biscuits and sweets) and fizzy drinks
• Eat less salt: much of the salt we eat is hidden in ready meals, cereals and sauces. Eating too much salt can raise your blood pressure and make you more likely to suffer from stroke and heart disease
• Eat at least five portions of fruit and vegetables every day. This could include fruit juice for breakfast, a side salad for lunch and a portion of vegetables with your evening meal
• Include starchy, energy-giving foods, such as grains, bread, potatoes, pasta and rice as part of your main meal
• Choose brown bread, wholemeal pasta and brown rice, as wholegrain foods contain more fibre and other nutrients than refined foods, such as white bread and rice
• Eat two servings of protein-rich foods every day, such as poultry, lean meat, fish, cheese, beans and pulses
• Aim to have oily fish, such as mackerel, trout and salmon, at least twice a week. These are an excellent source of protein and contain essential fats, minerals and vitamins
• Reduce the amount of food high in saturated fat (cakes and biscuits, butter and lard, pies and sausages). Your diet needs to include some fat, but look for foods rich in unsaturated fat, such as oily fish, avocados, nuts and seeds
• Drink plenty of water. It is recommended that you drink at least six to eight cups of water a day

Keep active

The Department of Health recommends at least 30 minutes' moderate exercise five times a week ⁽⁴⁾. This can be made up of three or four shorter bursts of activity that add up to 30 minutes.

The easiest way to get active is by building more exercise into your daily routine, for example by walking or cycling to work, or using the stairs instead of the lift.

Build up your levels of activity by making small changes:

• Get off the bus one or two stops early and walk the rest of the way
• At lunchtime, go for a walk and enjoy some fresh air
• Park your car a little further from the shops and walk the last bit
• Cycle instead of taking public transport or the car
• When you walk, speed up your pace a little and raise your heart rate
• Find out about sports facilities in your area and try something new
• Look into exercise or dance classes, if you find it boring to exercise on your own
• Join a team, such as five-a-side football or volleyball, or get a friend to become your gym or running partner so you can motivate each other

Is there a magic weight-loss pill?

The best way to lose weight is to eat a healthy diet and to take regular exercise. However, GPs can prescribe drugs such as orlistat and sibutramine to some obese patients to aid weight loss.

These medications are not a 'magic' solution and have side-effects like all drugs. You should only use them as part of a medically supervised weight loss programme.

Never buy weight loss medication via the internet or take it without your doctor's knowledge, as this type of medication should only be obtained on prescription.

Orlistat works by blocking enzymes in the gut that digest fat. Undigested fat is therefore passed out of the body with the stools (faeces), rather than being absorbed. For the drug to have any effect, you must eat less food and reduce your fat intake. Side-effects can, however, include diarrhoea and flatulence.

To be prescribed orlistat, your BMI must be 30 or above ⁽⁵⁾, or 28 or above if you have another health condition, such as diabetes or high blood pressure ⁽⁴⁾. You will also need to be between 18 and 75 years old. Children and pregnant or breastfeeding women should not take orlistat ⁽⁴⁾.

Sibutramine reduces appetite and makes you feel full, even if you have eaten less food. It still requires a healthy, calorie-controlled diet and increased exercise levels and is not a short-cut to weight loss.

Sibutramine is only recommended for patients who have difficulty in losing weight and have a BMI of 30 or above (or 28 or above for people with diabetes). You must also be between 18 and 65 years of age ⁽⁶⁾.

Weight loss surgery

Surgery can be used in cases where people have not managed to lose weight with dieting and medication. It is only carried out in certain NHS hospitals and can be risky ⁽⁷⁾.

Weight loss following surgery can be dramatic, as the stomach or gut can no longer absorb food properly. Some methods require you to change your diet for the rest of your life, particularly if your stomach is made smaller through surgery.

You should talk to your doctor about which option is best for you.

Types of weight loss surgery:

Laparoscopic adjustable gastric banding

The surgeon will place a constricting ring around the stomach. The bands contain an inflatable balloon which can adjust the size of the ring and regulate food intake ⁽⁸⁾

Sleeve gastrectomy

The surgeon removes most of the stomach, leaving a sleeve-shaped cylinder of stomach with reduced capacity. If you have this type of procedure, it is irreversible ⁽⁸⁾

Gastric bypass

The surgeon creates a small gastric pouch bypassing the duodenum and proximal jejunum, which stops you absorbing fats from your food (malabsorption) ⁽⁸⁾

Biliopancreatic diversion or duodenal switch

More extensive than a gastric bypass, with the gastric pouch joined to the ileum, producing a more extreme malabsorption of food ⁽⁹⁾

Gastric stimulation

Uses an implanted pacemaker-type device to produce electrical gastric stimulation ⁽¹⁰⁾

Intragastric balloon

The surgeon places a silicone balloon inflated in the stomach to promote a feeling of satiety (fullness). There is no strong clinical evidence to assess how affective this operation is and there can be complications, such as ulcers ⁽¹¹⁾

Infolinks:

• National Health Service
• British Heart Foundation
• Foods Standards Agency
• NHS Five a Day
• Eatwell at the Foods Standards Agency
• Sport England: Get Active
• Active Places
• Walking the Way to Health
• Everyday Cycling
• MEND programme