Low-Carb Lowdown (Part 1)

On July 31, 2005, the low-carbohydrate diet was declared dead by the popular media. The occasion was the filing of a Chapter 11 bankruptcy by Atkins Nutritionals, a company founded by the godfather of the low-carb diet, Robert Atkins, M.D. Atkins himself wasn’t around to watch his company fade, since he had died two years earlier after slipping on an icy sidewalk in New York and going into a coma.

Although Atkins’ name was most associated with the low-carb diet, he was hardly the first to advocate that kind of eating plan. The use of a low-carb diet dates back to antiquity—the fifth century B.C. to be exact. A two-time Olympic long-distance champion named Stymphalos attributed his athletic success to following a diet of mostly meat. The legendary Greek wrestling champion Milo of Croton, who won no fewer than five Olympic wrestling events between 536 and 520 B.C., was reputed to eat an average 19 pounds of beef daily to attain his prodigious strength. Milo is also famous for using the first progressive-resistance exercise regimen, which consisted of lifting a calf every day, even when the calf became a bull. Whether that bull eventually became a source of protein for Milo isn’t recorded.

The first popular low-carb diet was offered by William Banting, a retired London undertaker who claimed to have shed 45 pounds of fat in 1863 by eating a low-carb diet. The diet was suggested to him by Dr. William Harvey after Banting consulted him about a recurrent earache. The doctor felt that Banting’s symptoms stemmed from the excess fat in his ear. Banting was so impressed by the results of his diet that he published it in a brief book called Letter of Corpulence that became the first commercial diet book.

In the early 20th century, Arctic explorer Vilhjalmur Stefansson lived among the native Inuit people and adopted their 90 percent meat and fish diet, devoid of carbohydrates. While consuming this diet, Stefansson noted that he and his fellow explorers remained healthy. In fact, the only side effect occurred when one intrepid explorer decided to eat fish only. That led to nausea, which was rapidly rectified when fat was added to his diet.

When Stefansson reported on the diet in a series of published articles, medical professionals expressed skepticism concerning the effects of not eating carbohydrates. Stefansson elected to prove his contention about the safety of the diet by living in a metabolic ward at Bellevue Hospital in New York while eating a carb-free, meat-based diet for one year. During that time he was closely observed by medical researchers. The results, published in the Journal of the American Medical Association in 1928, showed zero adverse effects from the diet, not even a vitamin deficiency.

Since then, numerous versions of the low-carb diet have appeared. The most popular was Atkins’ plan, first published in 1972. The cornerstone of Atkins’ and all other low-carb diets is that bodyfat is largely the result of excess insulin release. Insulin is required for the uptake of glucose into cells, but it also stimulates the synthesis of bodyfat.

According to low-carb-diet proponents, those who have excess bodyfat produce too much insulin because their enlarged fat cells make them insulin insensitive. Carbs are considered the primary culprit because sugars trigger the greatest release of insulin. A lesser-known fact is that protein also triggers insulin release, explaining why modern postworkout supplements emphasize a combination of protein and simple carbs—taken together, the nutrients maximize insulin release more than either alone.

Critics of low-carb diets point out that it’s calories that count when it comes to bodyfat loss. Many suggest that insulin alone doesn’t stimulate excess bodyfat in the absence of an excessive calorie intake. Studies with diabetics and nondiabetics in which the subjects ate an identical number of calories—the only difference being that one group also injected insulin—demonstrated that those injecting the insulin had significantly more bodyfat. Isolated-fat-cell studies also show that insulin alone doesn’t trigger bodyfat synthesis. If you add sugar to the mix, however, bodyfat synthesis goes up significantly.

Still, the debate rages about the effectiveness and safety of low-carb diets. Studies published in the New England Journal of Medicine in 2003 found that while low-carb diets are effective for weight loss, it was the drop in calories on the diets that caused the fat loss, not the decreased carb intake.1 What the authors didn’t explain, however, was the average 37-pound weight loss for those on low-carb regimens, compared to the four-pound weight loss for those on a high-carb diet.

Another study found that when compared to a lowfat, high-carb eating plan, low-carb diets proved superior for spurring bodyfat loss for the first six months. After a year, however, both diets showed similar results, which can be explained by the gradual addition of carbohydrates to the diets of initial low-carb dieters. Those on the low-carb diet showed some beneficial changes in cardiovascular risk factors, such as increased high-density lipoprotein and lowered blood triglycerides.2 A more recent survey comparing various diets showed that the low-carb diet proved superior to high-carb, lowfat diets for fat loss.

When Atkins released his book Dr. Atkins’ Diet Revolution in 1972, he was promptly pilloried by his colleagues in the medical profession. The acerbic critiques targeted Atkins’ espousal of a high-fat intake, even saturated fat, the alleged dietary demon linked to cardiovascular disease. Atkins, a practicing cardiologist, felt that insulin was a more direct cause of cardiovascular disease than saturated fat. He believed that an increased fat intake wasn’t a problem because you’d use the fat as an energy source in the absence of carbohydrate. ALL Research over the years has proven that Atkins’ assertions were correct. A low-carb diet offers cardiovascular protection. Its higher fat content raises HDL, which helps the body remove excess blood cholesterol. Lowfat, high-carb diets are known to lower HDL while raising levels of triglycerides, or blood fats. low-carb diets consistently lower triglycerides, an effect amplified when you add fish oil supplements to your diet. Low-density lipoprotein, often referred to as the bad cholesterol, because of its association with cardiovascular disease, is also favorably affected by low-carb diets. It turns out that the smaller, denser forms of LDL are more dangerous than the larger, more buoyant forms. Research shows that a low-carb diet favors the formation of the larger, benign LDL molecules.3 That’s why the low-carb diet is now suggested as an effective form of therapy to treat the metabolic syndrome, a harbinger of cardiovascular disease and diabetes.

A recent study of guinea pigs, which process cholesterol much as humans do, revealed one way that low-carbohydrate diets help control cholesterol. A high intake of dietary cholesterol increases the activity of an enzyme in the liver that synthesizes fat. But when the guinea pigs are put on low-carb diets, the enzyme is suppressed, despite a high amount of cholesterol in the animals’ diets.4 Another recent animal study found that a high-fat, low-carb diet helps prevent the enlarged heart associated with high blood pressure.5

Human studies likewise confirm the beneficial effects of low-carb dieting. One example is a recent study involving moderately obese human subjects who followed two types of low-carb diets. One featured foods high in saturated fat, such as meat, similar to what Dr. Atkins originally suggested. The other diet focused on fish, poultry and shellfish that contained a high content of polyunsaturated fats, which are suggested for reducing elevated blood cholesterol. After 28 days both diets proved equally effective in stimulating weight loss, and neither diet adversely affected blood cholesterol, although the diet that had more polyunsatured fat more effectively lowered triglycerides.6

While some saturated fatty acids, such as palmitic acid, can increase cholesterol, they don’t do so in the presence of polyunsaturated fatty acids, such as linoleic acid, found in vegetable oils and food. The authors observe that fears of soaring cholesterol from eating low-carb diets don’t make biological sense. Saturated fats are most potent in increasing HDL, while polyunsaturated are the least efficient.

Another study found that eating a low-carb diet seemed to trigger selective bodyfat loss. Seventy percent of the subjects, who were all men, lost more fat on a low-carb diet, even though they ate more calories. They also lost more fat in the chest and stomach—highly significant because fat stored in those areas is more metabolically active and is linked to cardiovascular disease, high blood pressure, diabetes and the metabolic syndrome. In fact, they lost three times as much fat in the trunk area as those on a lowfat diet.7

While a diet high in cholesterol and saturated fat is often linked to the onset of Alzheimer’s disease, that correlation may not be correct. A recent animal study found that a low-carb diet lowered a protein that accumulates in the brains of those with Alzheimer’s disease and is considered a major cause of the disease.8 That makes sense because a protein in the brain called insulin-degrading enzyme is known to break down both beta-amyloid, the toxic protein in Alzheimer’s, and insulin. Eating too much carbohydrate increases insulin. That makes the insulin-degrading enzyme focus on insulin, enabling excess beta-amyloid to accumulate in the brain, which has led many researchers to refer to Alzheimer’s as “type 3 diabetes.”

Recent animal studies also show that low-carb diets, by lowering both insulin and insulinlike growth factor 1, may prevent prostate cancer.9 In contrast, diets high in refined carbs are linked to prostate cancer.10

So are low-carb diets dead? Apparently not for those who want to live longer. In Part 2 we’ll discuss why low-carb diets are effective.

References
1 Bravata, D.M., et al. (2003). Efficacy and safety of low-carbohydrate diets. NEJM. 289:1837-1850.
2 Foster, G.D., et al. (2003). A randomized trial of a low-carbohydrate diet for obesity. NEJM. 348:2082-2090.
3 Sharman, M.J., et al. (2004). Very-low-carbohydrate and lowfat diets affect fasting lipids and postprandial lipemia differently in overweight men. J Nutr. 134:880-885.
4 Torres-Gonzalez, M., et al. (2007). Carbohydrate restriction alters hepatic cholesterol metabolism in guinea pigs fed a hypercholesterolemic diet. J Nutr. 137:2219-2223.
5 Okere, I.C., et al. (2006). Low carbohydrate/high fat diet attenuates cardiac hypertrophy, remodeling, and altered gene expression in hypertension. Hypertension. 48:1116-1123.
6 Cassady, B.A., et al. (2007). Effects of low-carbohydrate diets high in red meats or poultry, fish, and shellfish on plasma lipids and weight loss. Nutr Metab. 4:23.
7 Volek, J.S., et al. (2004). Comparison of energy-restricted very-low-carbohydrate and lowfat diets on weight-loss and body composition in overweight men and women. Nutr Metab. 1:12.
8 Van der Auwera, I., et al. (2005). A ketogenic diet reduces amyloid beta 40 and 42 in a mouse model of Alzheimer’s disease. Nutr Metab. 2:28.
9 Freedland, S.J., et al. (2007). Carbohydrate restriction, prostate cancer growth, and the insulin-like growth factor axis. The Prostate. In press.
10 Venkateswaran, V., et al. (2007). Association of diet-induced hyperinsulinemia with accelerated growth of prostate cancer (LNCaP) xenografts. JNCI. 99:1793-1800. IM Supplements for Low-Carb Dieters

Using certain food supplements makes low-carb dieting easier, safer and more efficient.

• Potassium and magnesium. These minerals are particularly beneficial during the initial stages of a low-carb diet to prevent muscle weakness and fatigue. Aim for at least 450 milligrams of magnesium and 2,000 milligrams of potassium daily. An alternative is to take a well-balanced multimineral supplement that contains both minerals, plus calcium, another mineral often in short supply in people who follow low-carb diets. In fact, a daily vitamin-and-mineral supplement provides additional nutritional insurance.

• Fish oil. Omega-3 fatty acids found in fish oil lower elevated blood triglycerides and lower insulin resistance. Some studies suggest that fish oil may also stimulate fat oxidation when combined with exercise. In addition, it significantly adds to the natural triglyceride-lowering effects of low-carb diets, as does aerobic exercise. Aim for a daily intake of five grams or more.

• Creatine. While meat, a staple of low-carb diets, is rich in creatine, it wouldn’t hurt to maximize muscle energy stores with a creatine supplement. That’s especially true for bodybuilders, who depend on the ATP-creatine energy system in muscle to fuel exercise. Taking creatine with a rapidly absorbed protein source, such as whey, removes the necessity of taking it with a simple carb that may trigger excess insulin release.

• Glutamine. Glutamine helps replenish glycogen stores in the body and can act as an alternative fuel source during a diet. Low-carb diets tend to promote the increased excretion of glutamine, about 25 percent above normal levels. Get five to 20 grams daily.

• L-carnitine. This amino acid product helps the body use fat as an energy source and may be particularly useful during low-carb diets. The goal is two to three grams daily in divided doses, with one dose taken 60 minutes prior to training.

• 5-HTP. It’s a precursor of serotonin, a brain chemical related to a craving for carbs. Taking 5-HTP may help prevent bingeing on sweets. The dose is 100 to 300 milligrams daily. Don’t take it prior to training, as it can cause drowsiness.

• Total milk protein. High protein intake is key to success during low-carb dieting. Milk protein is easily digested and low in carbs. A useful alternative is a milk protein-based meal-replacement product low in carbs (fewer than 25 grams of carbs per serving).

• Branched-chain amino acids. These are not required if you opt for a milk protein supplement. They’re useful for preventing muscle loss if you’re engaging in aerobic exercise while dieting. Taking five grams prior to training works well.

• Beta-alanine. Beta-alanine improves muscle endurance and prevents premature fatigue during training. Take three to six grams daily in divided doses.

• Protein-and-carb recovery drink. You can have one either before or after workouts without its adversely affecting the rate of fat loss. Taking it prior to training imparts a muscle-sparing, anabolic effect. Taking it after promotes glycogen synthesis and amino acid uptake into muscle for more efficient workout recovery.

—J.B.