Is the currently chic carb-free Atkins diet beneficial for lipodystrophy, or is moderation the key?
Despite the recent emphasis on dietary interventions to improve the metabolic disorders associated with lipodystrophy, new studies have explored whether the same diets recommended to improve lipids and insulin sensitivity -- which are based on evidence largely drawn from HIV-negative population studies -- can help with certain physical features of lipodystrophy, particularly central fat (abdominal) accumulation.
Of course, the jury is still out as to whether the fat gain reported by many people on HAART (Highly active antiretroviral therapy) can even be called lipodystrophy. Although increased abdominal fat is regarded as a core feature of lipodystrophy according to the HIV Lipodystrophy Case Definition Group, recent reports from the ongoing Fat Redistribution and Metabolism (FRAM) Study suggest that HIV-positive men and women with lipodystrophy actually have less visceral abdominal fat than their HIV-negative counterparts.
The U.S. guidelines generally recommend eating more fiber and reducing fat intake. When high triglycerides are an issue, saturated fats should be replaced with monounsaturated fat or omega-3 polyunsaturated fats (e.g., fish oils). When wasting and lipid disorders occur together, however, wasting should be addressed first (i.e., fat may need to be increased to add calories), since it is riskier in terms of HIV disease progression.
The latest British HIV Association (BHIVA) guidelines also suggest that dietary advice may play a role in the prevention and management of lipodystrophy. The guidelines authors suggests a "Mediterranean diet" rich in omega-3, fiber, and fruits and vegetables. This diet is known to reduce risk factors for cardiovascular disease in the general population.
There is some evidence that this low-fat, omega-3-rich, high-fiber diet can improve metabolic function in people taking anti-HIV treatments. A U.K. study, which compared lipid-lowering agents with dietary advice found that the latter showed modest effects. But a Spanish team reported that while a low-fat diet in people on HAART with high lipids had moderate success in lowering lipids it had almost no impact on central fat accumulation. A U.S. study of 62 men and 23 women with lipodystrophy found that, on average, people who consumed more dietary fiber had lower insulin levels. And a laboratory study reported that omega-3 polyunsaturated fats may have a protective impact on fat cells exposed to protease inhibitors.
But will these strategies really help you reduce your risk of cardiovascular disease as well as help you lose (apparently) lipodystrophy-associated excess fat without worsening fat loss elsewhere?
Unfortunately, more than six years after the first reports of lipodystrophy, there are no reliable studies comparing different dietary strategies in people with HIV. Alternative weight loss strategies such as the Atkins diet and the low glycemic index diet (the GI diet) have not been studied. However, current theories about the causes of central fat accumulation seem to suggest that diets which target insulin sensitivity and sugar metabolism may play a role in reversing this part of lipodystrophy syndrome.
The factors driving body fat changes and metabolic abnormalities in HIV-positive people have not been definitively established. Two classes of anti-HIV drugs -- protease inhibitors (PIs) and nucleoside analogue reverse transcriptase inhibitors (NRTIs) -- are known to contribute to the syndrome but exactly how remains the subject of speculation and research.
There are several theories regarding how HIV and/or anti-HIV drugs might be causing peripheral fat loss (lipoatrophy), fat gain (lipohypertrophy) and metabolic disorders.
The fashionable Atkins diet has four phases: a strict two-week induction period where carbohydrate (carb) intake is limited to 20 grams each day; an ongoing weight loss phase where you can eat up to 100 grams of carbs daily, and the pre-maintenance and maintenance phases where carb intake remains restricted but you maintain a stable weight. Carbohydrates include all foods made up of sugar or starch, including bread, pasta, fruits and vegetables.
Two studies published in the New England Journal of Medicine earlier this year found that this low-carb strategy does lead to weight loss and improves metabolic parameters in HIV-negative people. In one of the studies, 132 obese people with a high prevalence of diabetes or pre-diabetes (insulin resistance) were randomized to either a low-fat, calorie-restricted diet or a low-carbohydrate diet. Average weight loss was 5.8 kg [12.78 lbs] in the low-carb group and 1.9 kg [4.19 lbs]in the low-fat group -- a statistically significant difference. Measure of metabolic function also improved significantly in the low-carb group -- triglycerides fell irrespective of medication and insulin sensitivity improved.
However, despite some anecdotal success stories from HIV-positive people with central fat accumulation, experts unanimously agree that the Atkins diet may have serious health consequences for HIV-positive people in both the short- and long-term.
According to Dr. Devi Nair, a lipidologist from London's Royal Free Hospital, and two specialist HIV dieticians -- Pip Greenop and Simon Sadler from Australia, where the Atkins diet is also currently in vogue -- Atkins is an unbalanced and restrictive diet which is not sustainable or safe in the longer term, despite some apparently attractive short-term benefits.
The Atkins diet raises many specific concerns for people with HIV infection:
The nature of the weight loss seen in people on Atkins is also suspect. Initial weight loss comes from fluid (water) loss, as the body raids its stores of glycogen.
Dietician Jennie Brand-Miller from the University of Sydney points out that a randomized study comparing four diets has shown that people on a low glycemic index (GI) diet lose more fat than people on a high protein diet, even though overall weight loss is comparable. The low GI diet also aims to reduce blood glucose and promote insulin function and weight loss. Could this way of eating be a less radical alternative to Atkins?
A case study published last year reported successful treatment of lipodystrophy and metabolic improvements using a high-fiber, low GI diet plus regular aerobic exercise and weight training. The man's diet was made up of 15% protein, 30% fat and 55% carbs including at least 25 grams of dietary fiber daily. After four months, the man had experienced a 52% reduction in visceral fat and his weight had fallen by a total of 8 kg [17.6 lbs]. His LDL or "bad" cholesterol had fallen by 30%, fasting insulin by 3.5% and insulin resistance by 15%.
Key elements of the low GI strategy have been successfully incorporated into the management and prevention of diabetes, insulin resistance and hyperglycemia.
The glycemic index is a way of comparing foods in terms of how quickly sugar is absorbed into the blood stream. Some foods such as potatoes, white flour products and rice cakes are processed quickly, producing a rapid and dramatic peak in blood sugar levels. These simple carbohydrates are called high GI food. Other foods are turned into blood sugars more slowly, and produce a less dramatic and more enduring rise in blood sugar. These are complex carbohydrates, or low GI foods. Examples include al dente pasta, brown rice, wholegrain bread, apples, chickpeas and oatmeal.
A detailed list of GIs for over 750 types of food can be found free on the Internet in the American Journal of Clinical Nutrition at www.ajcn.org/cgi/content/full/76/1/5.
A low GI diet involves reducing your intake of refined foods, potatoes and rice, and eating more fiber and unsaturated fats. Simple changes such as replacing white bread with whole meal bread, or making sure that you never eat simple carbohydrates on their own (by adding unsaturated fat and/or protein), can help reduce blood sugar levels after eating. This may help with sugar metabolism and improve insulin sensitivity.
At this stage, there is no clear scientific evidence that any particular dietary strategy will help you lose your belly while keeping your facial or limb fat loss to a minimum. If you are considering changes to your diet, discussion with your doctor and/or a dietician is recommended. Standard lipid-lowering or fat loss advice is not always appropriate for everyone with HIV.
Additionally, no diet can work in isolation: exercise and other lifestyle changes, particularly stopping smoking, are known to be other key elements in maintaining a healthy heart.
It is also crucial that dietary changes (e.g., reducing fat intake) do not reduce absorption of your HIV medications, or cause you to lose weight if you are already wasting.
The final point to bear in mind is that attempts to lose your central fat accumulation through regular intense aerobic exercise may worsen fat loss in your face and limbs. Although weight training to build muscles may help to offset this problem, adding anabolic steroids to your muscle-building regime can actually worsen facial lipoatrophy.
All You Can Eat?
The best way to feel good about your body and your blood fat levels is to pick and choose -- buffet-style -- what suits you best. General sound advice includes:
Consultation with a specialist HIV dietician is recommended before embarking on a new dietary strategy.
This article was first published in AIDS Treatment Update issue 130 and is reprinted with permission from NAM (www.aidsmap.com).