Regardless of HIV status, the equation is simple: Your body weight is a result of how many calories you take in through food and how many calories you use up through all the activities of your day. This equation is called energy balance, and HIV can affect energy balance by increasing the amount of energy used up in the fight against the virus.

Your weight is an indicator of whether or not your energy needs are being balanced by your food intake. In this section we take a look at weight and what to do when weight gets too low or too high.

Energy Balance

The body requires fuel each day to have energy to perform all the activities required to sustain life, from the pumping of your heart to your walk in the park. Calories are the measure of energy or fuel that food provides. All foods provide calories: carbohydrates and proteins provide 4 calories per gram and fat provides 9 calories per gram.

REE (resting energy expenditure) is a measure of the number of calories needed by a person when the body is at complete rest. Research has shown that asymptomatic people with HIV have an REE that is slightly increased, by about 10%, because of the widespread effects of chronic inflammation caused by the virus.

Keeping Energy in Balance

• People with HIV who are asymptomatic and at an ideal weight need 30 to 35 calories per kg body weight per day (14 to 16 calories per pound).
• To lose weight, decrease calories by 300 to 500 calories per day. This can be done by cutting out sweets and high-fat snacks and decreasing portion sizes.
• To gain weight, increase calories by 300 to 500 calories per day. One peanut butter sandwich and a glass of milk provide about 400 calories.

Weight

Keep track of your weight as one way to monitor your health.

Your body weight is an important indicator of your health and nutritional status. Unwanted weight changes can be the first sign that there is an underlying health problem. Weighing yourself once tells you if your weight is in a healthy range, or if it has changed compared to your usual weight. Tracking your weight over time reflects what's going on with your health.

Experts classify people as being underweight, ideal weight, overweight or obese. Different degrees of health risk are assigned to the different groupings. The BMI (body mass index) is one tool you can use to classify your weight. (BMI is calculated as weight [in kilograms] divided by height [in metres] squared.) The BMI has limitations in that it does not factor in gender, age, ethnicity or body composition (see next section). However, it remains the standard for evaluating a person's health risk according to their weight. See Appendix C for a chart that will help you quickly determine your BMI.

The following is the classification system for BMI developed by the World Health Organization. For people living with HIV, a BMI below 20 is considered underweight.

Body Composition

Body weight doesn't tell the whole story about your health. Picture two people, one muscular and one obese, who each weigh the same. Obviously these two people would be in very different states of health. Now imagine somehow being able to separate the different substances that make up your body (fat, muscle, etc.) and weigh each of them. This would give you a useful inventory of what your body is made of -- your body composition. This inventory is often divided into two parts, the total amount of bodily fat, called fat mass, and everything else, called fat-free mass.

Fat is present in the body as essential fat and stored fat. Essential fat is required for normal metabolism and the physical structure of the body. The amount of essential fat is fairly stable and does not change easily. The other kind of fat, stored fat, acts as a reserve of energy, similar to a savings account at a bank. Stored fat is the most variable body compartment: It changes depending on energy balance. Most stored fat is found just under the skin. This is called subcutaneous fat, and it is the tissue that decreases in people who have fat wasting, or lipoatrophy (see "Lipodystrophy," Chapter 5).

Fat-free mass, also called lean mass, can also be subdivided into body cell mass and extracellular mass. Extracellular mass is made up of the body's "inert" parts: water and fluids, bones and structural tissues. Body cell mass includes the muscles and organs. Muscle tissue is the largest reservoir of body cell mass and the most susceptible to change. Because it is critical for survival, a loss of even 5% of body cell mass is considered severe.

Studies have shown that people with HIV sometimes lose body cell mass over time even though weight may stay the same. This is why it's important to monitor your body composition rather than just your body weight and to try to maintain a good amount of muscle mass.

Analyzing Your Body

• Try to find a dietitian who can perform body composition analysis.
• Measure your own waist at a point just above the belly button to see if you are at increased risk of heart disease. If you're a man, your risk is increased if your waist is greater than 102 cm (40 inches). For women, the risk is higher when your waist is larger than 88 cm (35 inches).

Weight Loss

Weight loss continues to be a difficult problem for people with HIV. Studies have shown that even a small amount of unwanted weight loss increases the chance of getting sick and dying. Whenever weight is lost, some comes from stored body fat and some from lean tissue. How much is lost from those two compartments depends on the underlying cause of the weight loss.

When weight loss is due to not consuming enough calories -- called starvation in medical terms -- about 40% of the weight lost comes from lean mass and 60% from fat. When there is an infectious process with fever, the body develops a stress response to the infection and up to 80% of the weight lost will be from lean mass and only 20% from fat. This is because the body is rapidly breaking down muscle to provide the ingredients needed to fight the infection. This type of weight loss is more serious and more difficult to reverse.

Be sure to do something about unwanted or unexpected weight loss right away.

In HIV disease there are many factors that cause weight loss, but not consuming enough calories is generally the driving force. If you have any symptoms or side effects that make it hard to eat, talk with your doctor or dietitian right away. It is important to prevent weight loss and the downward spiral of malnutrition. See Chapter 6 for ideas on how to deal with these and other issues.

The primary strategy for treating weight loss is to increase macronutrient intake to the level needed to promote weight gain. This is achieved with a high-calorie, high-protein diet and a multivitamin-mineral supplement (see "Weight loss and wasting," Chapter 6).

Weight Gain

If you are overweight or obese, losing even 5% of your weight will have health benefits.

Being overweight or obese is increasingly common among people with HIV, as it is among the general Canadian population. The reasons for this are unclear but may be related to the fact that people with HIV are living longer and better. Obesity -- defined as a BMI over 30 -- comes with its own set of health risks, including heart disease, diabetes, high blood pressure, gallbladder disease, fatty liver disease, loss of bladder control and some cancers. Years ago it was unheard of to recommend that a person with HIV lose weight but it is now clear that the health risks of obesity outweigh the risk of developing wasting in the future.

Losing weight and keeping it off is difficult and takes dedication. There is no shortage of weight-loss diets, and the best ones emphasize healthy, balanced eating that can be sustained over a long period. Many of the so-called fad diets work initially, but they are so restrictive that before long people go back to their old eating habits and regain all the weight they lost.

When considering a weight-loss diet that eliminates food groups or includes only a few foods, ask yourself if this will meet your needs to stay healthy. Rather than "going on a diet," which tends to be short-lived, try to see this as a long-term project for improved health. And think about including some exercise. In fact, the best predictor of long-term success in weight loss is physical activity. Exercise builds lean body mass but most importantly uses energy, which means burning calories.

Working on Weight Loss

Getting Started

• Losing weight requires patience and commitment.
• Get some professional help to be sure weight goals are realistic and nutritional needs for HIV are not compromised.
• Get physical -- exercise is the best predictor of success.

Other Tips

• Become more aware of your food choices and eating behaviour. Think about what you are eating instead of operating on automatic. Some people find it helpful to keep a food journal and write down everything they eat.
• When eating, focus on it; don't watch TV, read or do other activities. Be aware of tastes and textures and feelings of satisfaction or fullness.
• Identify and change the things that stop you from making healthy food choices or getting exercise (e.g. don't keep foods that you are trying to avoid, like potato chips or chocolate bars, in your home). Decide which are most important and then work on one at a time.
• Set realistic goals that will work and make them specific (e.g. instead of "I will eat more vegetables," say "I will eat 3 portions of vegetables today").
• Select three favourite low-calorie emergency snack foods and have them available for those times when you get hungry. Plan ahead so you don't act on impulse when you get hungry.
• Portion your food out on a plate rather than eating from the package. You'll be less likely to overeat.
• Try to plan meals and snacks. Make sure the groceries you buy help you eat according to your plan.
• Move your body. Walk, swim, bike or use the stairs more often. Regular daily exercise is the best way to lose weight and keep it off. Plus, you will be stronger, healthier and have better mental health.
• A slip is just a slip. Everyone has days when it's hard to stick to the eating plan. Try to see it as a slip, not a failure, and start over again.

Exercise

Try to be physically active every day for improved energy, strength and health.

Physical activity is a vital part of health and well-being. Maintaining daily activity increases energy, strength and independence and can also help to reduce stress. People who are active and have generous amounts of body cell mass also recover more quickly from illness. Canada's Food Guide recommends getting 30 to 60 minutes of physical activity every day. This does not have to be done all at once but can be added up in 10 minute increments.

The main types of exercise are resistance training (e.g. weight lifting), cardio or aerobic exercise (e.g. swimming or biking), and balance and flexibility exercise (e.g. yoga). Each type has different benefits. Get professional advice on the combination of exercises that is right for you.

Resistance training uses weight to increase body cell mass by building muscle mass. Weight lifting is the fastest way to build muscle but it is not the only way. Resistance exercises can also be done using stretch bands, exercise balls and the body's own weight (e.g. push ups). Muscle burns more energy (calories) than fat, so increasing muscle mass increases the number of calories your body uses up in a day.

Cardio or aerobic exercise, which includes activities like running, walking fast, biking, skating and swimming, benefits heart health and improves insulin sensitivity. This type of exercise promotes weight loss. To get the most benefits cardio needs to be done 3 to 4 times per week for at least 20 minutes.

Balance and flexibility exercises, such as yoga or Tai Chi, help prevent injury and falls and should be included in your exercise program. For more information, read "Let's Get Physical" in the Spring/Summer 2005 issue of CATIE's The Positive Side, available at www.positiveside.ca.

Moving Your Body

Getting Started

• Build activity into daily living as much as possible. Even if you're not feeling well, try to keep as active as you can. Muscle mass is quickly lost if it's not used.

Other Tips

• Discuss any plans to start an exercise program with your doctor. And if exercise is new for you, get some advice from a trainer or physiotherapist.
• Start slowly and increase exercise level gradually to avoid injury.
• Take the time to warm up and stretch before and after exercising.
• It is not necessary to go to a gym for resistance exercise. Stretch bands and dumbbells can be used at home. Second-hand stores are good places to find dumbbells at low prices.
• Check with your local community centre for interesting programs or facilities. Some community centres offer reduced or free admission to people on disability pensions or income assistance.
• Find an exercise buddy to help keep you motivated.