Patient information from BMJ

Obesity - diet and exercise

Last published:Jan 04, 2022

Obesity - diet and exercise

If you're obese, you weigh much more than is healthy for you. This is the result of regularly eating more calories than your body uses. Your body stores the extra calories as fat.

Losing weight isn't easy. You'll need to change the way you eat and the amount of exercise you get. But if you make these changes you'll feel better and reduce your chance of many serious health problems.

You can use our information to talk with your doctor about which approach to weight loss is best for you.

What is obesity?

Being obese means being very overweight. This can greatly increase your chances of serious health problems such as:

• diabetes

• high blood pressure

• arthritis

• cancer, and

• heart disease.

When doctors talk about reaching a 'healthy' weight, they mean getting to a weight that lowers your risk of these health problems. It's not based on how thin you would like to look.

Most doctors use the body mass index (BMI for short) to work out whether you're at a healthy weight. Your BMI is a single number that's calculated based on your height and your weight. Doctors say someone is obese if their BMI is 30 or higher.

You might think that you don't eat a lot and that your weight problems must be caused by something else, such as a slow metabolism. But you can only become obese by eating more calories than your body uses. Unfortunately, to put on weight, you only have to eat slightly more calories than you use.

What are the symptoms?

If you are obese, you carry a lot of extra weight on your body. Carrying this extra weight may make you feel tired, or short of breath, or make your joints ache. You may also get skin irritation where your skin folds. Women may find that their periods become irregular.

Having extra weight around your waist has also been linked to having a higher chance of problems with your blood sugar, blood pressure, or cholesterol. This in turn may increase your chance of having heart problems.

What treatments work?

To lose weight, you need to take in fewer calories each day than you use. You can do this by following a weight loss programme.

Doctors usually recommend that people lose about 10 percent of their body weight over the first six months. If your BMI is 30 to 35, this will mean losing between 0.25 and 0.5 kilograms each week. If your BMI is above 35, you may need to lose between 0.5 kilograms and 1 kilogram a week.

Work with your doctor or practice nurse to set short-term, realistic goals.

Weight loss programmes

You have the best chance of losing weight if you combine a low-calorie diet with an exercise programme and behavioural therapy to help change the way you eat and exercise.

• A low-calorie diet means you eat fewer calories. This could mean eating smaller portions, and choosing foods with fewer calories. Men are usually advised to eat around 1200 to 1500 calories a day to lose weight. For women, the goal is usually 1000 to 1200 calories.

  There are many types of diet you can follow to lose weight, including low-fat diets, low-carbohydrate diets (such as the Atkins diet), the Mediterranean diet, and supervised diet plans (such as Weight Watchers).

  Some research suggests that low-carbohydrate diets work better than low-fat diets for the first six months, and that people find them easier to stick to. But there isn't much good evidence about what works best over the long term.

• Exercise is another essential part of a weight loss programme. The more exercise you do, the more calories you use. You'll probably need to do at least 30 minutes of physical activity on most days.

  If you don't currently exercise, it's a good idea to start slowly and work up to this amount. Your doctor can provide advice on how much exercise you should do. Bear in mind that exercise alone won't help you to lose much weight. You need to cut calories, too.

• Behavioural therapy includes ways to help you change the way you eat and your exercise habits. You have sessions with a health professional to learn to think and act differently so that you can stick to your weight loss programme.

Research suggests that you're more likely to lose weight and keep the weight off if your weight loss programme includes:

• regular contact with a health professional

• support from other people who are losing weight

• a low-calorie diet that lists the kinds of foods to eat and those to avoid

• weighing yourself regularly

• a personalised exercise plan

• a plan for how best to keep weight off when you've reached your target weight.

Home videos or self-help books probably won’t help as much as meeting regularly with a health professional to talk through your progress.

It's better to lose weight slowly and keep up the changes to your lifestyle. Crash diets or one-time bursts of exercise don't help to control your weight in the long term. The longer your weight loss programme lasts, the more likely you are to keep the weight off.

What will happen to me?

If you're obese, losing weight and keeping the weight off can be difficult. It will probably be easier if you get help from your doctor and follow a weight loss programme.

Here's what we know happens to most people who follow a weight loss programme:

• Most people lose about 5 percent to 10 percent of their weight within six months if they follow a programme that includes diet and exercise.

• Keeping the weight off can be a struggle. Most people put back on at least some of the weight they lose.

• Your best chance of keeping the weight off is to stay in a weight loss programme, with regular support from a health professional.

Although losing weight can be a challenge, the benefits are many. You will feel better and also have a much lower chance of serious health problems, including heart disease, cancer, diabetes, and arthritis.