As for anyone, it’s important to maintain a healthy body weight when you have HIV. Being overweight or underweight can cause problems for your health.

Maintaining a healthy weight is about balancing the energy you take in and use up. If you consume more energy (calories) than you use, you’re likely to gain weight. On the other hand, if you burn more calories than you eat, the chances are you’ll lose weight.

Weighing too little can weaken your immune system and cause bone problems. If you experience an unintended drop in your body weight, especially if it’s accompanied by symptoms such as diarrhoea, vomiting, fevers or pain, you should mention this to your doctor.See Unintentional weight loss for more information.

People who gain too much weight in the first year of starting HIV treatment may have an increased risk of developing type 2 diabetes and cardiovascular disease later in life. Getting advice from a dietitian during this first year of treatment is a good idea as they will be able to help you limit weight gain.

Finding the right balance over time allows you to achieve and maintain a healthy body weight. How and what you eat can help influence both your weight and the levels of fats and sugars in your blood.

Working out your body mass index (BMI) can provide an approximate idea of how healthy your body weight is for your height. It is calculated using your height and weight measurements. A BMI between 18.5 and 25 is considered to be within the healthy range. AsBMI calculations cannot distinguish between muscle and fat, they should only be used as a general guide. A useful tool that helps you to calculate your BMI is available on the NHS Choices website at: www.nhs.uk/tools/pages/healthyweightcalculator.aspx

There’s lots of advice and help available on eating well, and on choosing a healthier lifestyle to help you lose weight or maintain a healthy weight. You could start with the information on NHS Choices, at www.nhs.uk/livewell/goodfood or on the British Dietetic Association’s Weight Wise website: www.bdaweightwise.com.

The HIV organisation The Food Chain provides more information on eating well. Resources such as factsheets and recipes are available on its website. The Food Chain also offers a range of services, including free healthy eating courses and practical cookery classes, for people living with HIV in London. Contact The Food Chain on 020 7843 1800, email info@foodchain.org.uk, or visit its website: www.foodchain.org.uk.

The anti-HIV drugs commonly used today are much less likely to cause the body-shape changes (lipodystrophy) that some older drugs did. So if you notice an increase in your weight and accumulations of soft fat around your belly or in other parts of your body, this is likely to be routine fat gain associated with eating too much and not doing enough exercise. Having a large amount of tummy fat in particular makes you more likely to develop type 2 diabetes and heart problems.

Obesity is when a person is carrying too much weight for their height and it is becoming more common. Someone with a BMI over 30 is considered to be obese. It can cause a number of health problems. As well as type 2 diabetes and heart disease, it can also cause high blood pressure and can increase your risk of developing certain cancers. Being overweight or obese can shorten life expectancy by as much as six or seven years. 

Obesity is treated by losing weight, which will usually involve healthy, calorie-controlled eating and increasing the amount of exercise you do. This may mean you have to make some quite challenging lifestyle changes, but there is lots of help available. Talk to your healthcare team about the support they can offer, or see the end of this booklet for contacts of other organisations that may be able to help.

In some cases, where people are severely obese and find they cannot lose weight in other ways, there is the option of surgery. Like any operation, this has some risks attached and may not be suitable for everyone.