Obesity

Introduction

Obesity is carrying too much body fat for your height and sex. A person is considered obese if they have a body mass index or BMI (weight in kilograms divided by the square of your height in metres) of 30 or greater. Obesity can happen when you eat more calories than you burn off over a period of time.

The rate at which you burn off calories from food and drink is called the metabolic rate. This is often faster during growth spurts and puberty, but reaches a fairly steady rate by adulthood.

People who are very active generally have a higher metabolic rate, because they burn off calories faster through energetic activity. For example, a labourer working on a building site can need as many as 4000–5000 calories per day to keep an even weight. An office worker who uses a car to get to work and doesn’t exercise, may only need 1500 calories per day.

If the amount of calories provided by food energy is more than the calories burnt off every day in activity, the body stores the extra energy as fat. This is the body’s way of protecting itself in case of starvation. However, starvation in developed countries is extremely rare, and this insurance against ‘hard times’ is hardly ever needed.

Most of us have more food than we need, and much of it is higher in calories than the human body was originally designed to cope with. Fast food, high calorie snacks and large portions all mean it’s easy to take in more energy than we need. Obesity has now become one of the most serious medical problems of the western world.

Definition

Obesity can be measured in different ways:

An easy way is just to get on the scales and compare your actual weight with your ideal weight. Any calorie-counting book will give this information.

A more scientific way is to calculate your Body Mass Index (BMI). This is your weight in kilograms divided by the square of your height in metres. In the UK, people with a body mass index between 25 and 30 are categorised as overweight, and those with an index above 30 are categorised as obese.

Modern gyms and some weighing scales can electronically measure the percentage of your body weight that is fat, and can compare this with what would be ideal for you.

Facts

Obesity is fast becoming the developed world’s biggest health problem - over 30,000 deaths a year in England are caused by obesity alone. Obesity related deaths are second only to smoking.

Adult obesity rates have nearly quadrupled in the last 25 years – now two thirds of UK adults are overweight. Of these, 22 per cent of men and 23 per cent of women are obese. This means they are at least two to three stone overweight and seriously putting their health at risk.

According to figures from the National Audit Office, being obese can take up to nine years off your lifespan. It also makes you far more likely to develop a range of health problems including diabetes, heart disease, stroke, osteoarthritis, high blood pressure, gallstones, infertility and depression. Combined with lack of exercise, obesity contributes to one third of cancers of the colon, breast, kidney and stomach.

Obesity is not just an adult problem. The number of obese children has tripled over the last 20 years. Now 10% of six year olds are obese, rising to 17% of 15 year olds. Childhood obesity shouldn’t be dismissed as ‘puppy fat’ – it is a strong indication of adult obesity and serious health risks in later life.

Symptoms

Being a little bit overweight tends not to cause too many noticeable problems, but once you’re carrying a few extra stones, symptoms will affect your daily life.

Day-to-day, obesity causes problems, such as shortness of breath, but the long term health risks that you can’t see are more serious.

The immediate symptoms of obesity include:

• Breathlessness
• Sweating a lot
• Snoring
• Difficulty sleeping
• Inability to cope with sudden physical activity
• Feeling very tired every day
• Back and joint pains

In the longer-term, obesity greatly increases your risk of:

• High blood pressure, heart disease and stroke
• High cholesterol levels (fatty deposits blocking up your arteries)
• Breast cancer in women
• Gallbladder disease
• Gastro-oesophageal reflux disease (when acid from the stomach flows up into the gullet) and associated problems
• Arthritis of the back, hips, knees and ankles
• Diabetes and difficulty controlling existing diabetes
• Polycystic ovarian disease
• Reduced life expectancy overall

Causes

Obesity doesn’t just happen overnight – it develops gradually from poor diet and lifestyle choices, and to some extent from your genes.

Some people tend to stay the same weight for years without much effort, whereas others find they put on weight quickly if they’re not careful. This could be due in part to your genes – scientists have discovered certain genes that make you feel hungrier, or that mean you take longer to feel full.

More important, though, are the lifestyle choices you make. Eating more calories than you need may be down to poor food choices – for example eating high fat, processed or fast food, rather than filling up on fruit, vegetables and unrefined carbohydrates, such as wholemeal bread and brown rice.

Bad eating habits run in families – rather than inheriting a slow metabolism, the habits learned from your parents can be important. Childhood obesity is a strong indicator of weight-related health problems in later life, showing that learned unhealthy lifestyle choices continue into adulthood.

Lack of physical activity is another important factor. Many of us have sedentary jobs in which we sit down for most of the day, rely on a car to get around, relax by watching TV or playing computer games, and don’t take regular exercise. If we are not active enough to use up food energy, the extra calories are stored as fat instead.

Medical reasons

In less than 1 out of every 100 cases there is a medical reason for obesity. Conditions such as Cushing's disease and an underactive thyroid are rare causes of weight gain.

Certain medicines, including some steroids and antidepressants, can contribute to weight gain.

Taking the contraceptive pill and quitting smoking may increase your appetite

Diagnosis

The Body Mass Index is currently used as the most accurate and reliable way of measuring how are overweight you are.

You can work out your own BMI using this calculation:

• Measure your height in metres and multiply the number by itself.
• Measure your weight in kilograms.
• Divide your weight by the answer you got in step 1.  The number you are left with is your BMI.

§         An ideal BMI for most people is between 20 and 25.

Treatment

The best way to prevent obesity is by eating healthily and doing regular exercise.

As obese children tend also to be obese in later life, it’s very important for parents to set the right example at home.

Diet:

Fruit and vegetables and unrefined carbohydrates and should make up the bulk of your diet. Chose brown and wholegrain carbohydrates and be sparing with high-fat additions, such as cheese, cream and butter. Aim for five portions of fruits and veg a day and vary the colour and type to get maximum vitamins.

Think about how you prepare food – steaming and grilling are healthier ways of cooking than frying and roasting. Go easy on the amount of butter and oil you add.

Try not to overeat – listen to your body and stop when you’re full. It can take up to 30 minutes for the stomach to register it’s full, so eat slowly and wait before tucking into seconds. Serve food in the kitchen, not from the table where you’ll be tempted to go back for more.

Cut down on high fat snacks, junk food and ready meals, which are often packed with fat and sugar and don’t fill you up. Dried fruit, oatcakes, yoghurt and fruit are healthier and will fill you up for longer.

Exercise:

Exercise doesn’t just burn up calories: regular aerobic exercise increases your metabolic rate, so that even in everyday life the body uses more calories overall. This effect is quickly lost once regular exercise stops.

Regular exercise increases appetite, but the faster metabolic rate means it’s easily burnt off, particularly if you make the right food choices as described above.

Exercising when you’re overweight can be tough because the extra weight means your body has to work harder. If you can, aim for 60-90 minutes of exercise a day (this is the recommended amount for people who are obese and trying to lose weight). Stick to moderate activities that increase your heart rate and get you sweaty and slightly out of breath. If you feel embarrassed about joining a gym, try gardening, swimming, badminton, or attending fitness classes specifically designed for people who are overweight.

In addition, try to fit more activity into your daily routine. Walk or cycle to work, and take the stairs rather than the lift. If you’ve never exercised before, a brisk 30 minute walk each day is a really good starting point.

Calories:

Work out your daily calorie requirement from a calorie-counting book, and keep a food diary for a week. Don’t change anything about your usual diet, but be ruthless in noting the amount and type of everything you eat and drink. From this, you can work out how many calories you’ve consumed compared with the amount you needed.

As well as showing you whether you need to cut your calories, keeping a food diary can also help you identify the types of food you are eating too much of. As well as recording what you eat, note down the time, place and how you feel. Mood often plays a big part in what we eat – feeling depressed, bored or tired can quickly lead to comfort eating. Shopping when you’re hungry, not making time to prepare a balanced meal, and stress can all lead to the wrong food choices as well.

Prevention

Calorie control

The most straightforward way of tackling obesity is to reduce the amount of calories you eat and exercise more.

Using the food diary technique, cut out 500 calories per day from what you’re eating. Keeping a diary may have revealed particular times when you overeat, or certain types of food that you are more inclined to binge on.
Finding other activities to do rather than eat, and not buying foods that will tempt you are obvious first steps in cutting out 500 calories. You should find that you are still able to enjoy a range of tasty options.

Increase the amount of aerobic exercise you do. We all need to do 30 minutes exercise five times a week to stay healthy, but if you want to lose weight, you should increase this to 60-90 minutes every day.
Pick moderate activities that you enjoy, such as swimming or gardening – aim to increase your heart rate and be sweaty and a bit out of breath by the end. Check with your GP that any planned activity is safe for you.  

Don’t aim to lose weight too quickly, or you could end up losing muscle rather than fat. Aim for ½ - 1 kg (1 – 2 lbs) per week. This means eating 500-1000 fewer calories than before you started the diet. You should lose 6-12 kg if you keep this up for three months.

Losing weight and keeping it off is a long-term commitment to yourself. It isn’t easy, and it’s important not to be disappointed with any minor increases along the way. It’s better to look at the overall progress, and remember that any weight loss will improve your health.

Drug therapy

Drug treatment for obesity is only available in extreme cases. You need to show you can loose weight on a calorie controlled diet before it is considered. Drug treatment is normally one part of a weight loss programme, and requires a long-term change in lifestyle for lasting results.

The part of the brain that controls how hungry we are is called the hypothalamus. It controls the hormones and chemical signals circulating in our blood that influence appetite.

Traditional weight-loss drugs contain amphetamine, which is a stimulant drug that increases the activity of certain brain chemicals. They increase the amount of noradrenaline and dopamine hormones in the blood, which stops you feeling as hungry. However, they are not suitable for long-term use and can have serious side effects, including high blood pressure, anxiety and restlessness.

Scientists are trying to develop new drugs with fewer side effects by looking at the relationship between fat and hunger. Fat produces a hormone called 'leptin', which makes you feel less hungry.

Orlistat

Orlistat works by blocking the action of body chemicals called enzymes which digest fat. The undigested fat is not absorbed into your body, and is passed out with your faeces (stools). You have to have made significant effort to lose weight through diet, exercise or changing your lifestyle before taking it. Even then, it’s only prescribed if you have:

• a BMI of 28 or more and other diseases related to weight, such as diabetes, high blood pressure, or high cholesterol; or
• a BMI of 30 or more.

Treatment with Orlistat must be combined with a low fat diet and other weight loss strategies, such as taking more exercise.

Treatment with Orlistat should only continue beyond three months if you’ve lost 5% of body weight, and beyond six months if you’ve lost at least 10% of body weight.

Side effects of Orlistat include fatty smelly stools, urgency to get to the toilet, oily spotting on your underwear, and wind. They are much less likely if you stick to a low fat diet.

Pregnant women, breastfeeding women, and children should not take Orlistat.

Sibutramine

Sibutramine is another drug that may be prescribed to help with weight loss. It affects brain chemicals called noradrenaline and serotonin to make you feel more full or satisfied with less food. Again you need to have made considerable effort to lose weight before it is considered. Even then, it is only prescribed if you have;

• a BMI of 27 or more and other diseases related to weight, such as diabetes, high blood pressure, or high cholesterol; or
• a BMI of 30 or more.

Sibutramine will only carry on being prescribed if you lose at least 2 kg within four weeks, and 5% of your initial weight within three months of starting treatment.

People with high blood pressure, heart disease, heart failure, peripheral vascular disease, arrhythmias (abnormal heart rhythms), or a history of strokes should not take Sibutramine.

Side effects are unusual, but can include constipation, dry mouth, difficulty sleeping, and increased blood pressure.

If either of these drugs is prescribed for you, you will also be offered advice, support and counselling on diet, exercise and behaviour changes.

Surgery

People with a BMI of 40 or more are described as morbidly obese. At this stage, the problem can be very hard to treat. Surgery may be considered to restrict the amount of food eaten, or to interrupt the digestive process.

Surgery also may be an option for people with a BMI of 35 – 40, who have life-threatening cardiopulmonary problems, (for example, severe sleep apnoea or obesity-related heart disease), or diabetes.

Surgery is not considered unless you have made significant efforts with other weight loss techniques first. Operations are only successful if followed up with long-term commitment to lifestyle change.

Obesity surgery is divided into three broad categories:

Restrictive operations: The size of the stomach is restricted so you feel full after a small amount of food. This usually involves putting a band around the upper stomach or by stapling or dividing the stomach.

Malabsorbtive operations: Part of the bowel is bypassed so that less food is absorbed during the digestive process.

Combination operations: The size of the stomach and the amount of food absorbed during digestion are reduced.

Healthcentral 2005

Back to the top