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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.
How HIV meds interfere with metabolism
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.
- Mitochondrial toxicity. Damage
to mitochondrial DNA by NRTIs, particularly stavudine (d4T),
may disrupt energy metabolism, damage cells and hasten programmed
cell death (apoptosis). This theory can account for a range
of symptoms including loss of fat tissue, high lactate levels
and peripheral neuropathy.
- Disruption to fat metabolism.
PIs disrupt lipid metabolism, leading to excess production
of triglycerides, cholesterol and lactate. PIs and/or NRTIs
may interact to undermine the making of fat cells and increase
programmed cell death, as well as disrupting production
of energy from fatty acids. Possible mechanisms include
the disruption of certain cytokines (chemical messengers
e.g. TNF alpha) and the effect of PIs on transcription factors
(e.g. SREBP1).
- Inhibition of insulin. Inhibition
of some glucose transporters by most protease inhibitors
may be one element causing insulin resistance. This may
be compounded by disruptions to fat cells and fat metabolism.
Insulin resistance may be driving central fat accumulation
and ‘buffalo hump’ by causing reduced uptake of
sugar, triggering a release of fatty acids into the blood.
- Chronic immune activation due
to HIV may contribute to some or all of these mechanisms.
Can the Atkins diet help with lipodystrophy?
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 Atkins diet is high in saturated
fats, and thus may contribute to elevated cholesterol and
the long-term risk of artery disease. Dr. Nair suggests
that a modified Atkins diet—which reduces, but does
not eliminate carbs (replacing extra carbs with more protein
and fats that are heart-healthy, like olive and fish oils)—may
be a healthier alternative.
- The body needs glucose. When glucose
consumption is dramatically restricted, the body accesses
its glycogen stores. If glycogen stores are not replenished
through dietary glucose, fatigue may occur and contribute
to muscle wasting. Maintaining muscle is know to preserve
immune function and slow disease progression in people with
HIV.
- Low consumption of fiber may
have negative effects. In people with HIV, treatment with
soluble fiber is often recommended to help control cholesterol,
relieve treatment-associated diarrhea, and maximize gut
health.
- Low consumption of carbs may
alter calcium metabolism, causing kidney stones (already
a risk in people taking indinavir) or reducing bone mineral
density, which is already a problem for certain people with
HIV, due to either HIV itself or HAART.
- A high-protein diet may be difficult
for people with kidney damage to tolerate, and since tenofovir
has been associated with kidney toxicity, caution should
be taken if on this drug and eating a high protein diet.
- A low-carb diet may remove many
B vitamins and antioxidant nutrients from the diet. Low
vitamin and mineral consumption may compound these deficiencies
in HIV-positive people.
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.
The low GI diet: a healthier alternative?
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 http://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.
Food for thought
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 knownto 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.
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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.