Tag Archives: low carbohydrate diet

Low-Carb Mediterranean Diet Beats Low-Fat For Recent-Onset Type 2 Diabetes

A low-carbohydrate Mediterranean diet dramatically reduced the need for diabetic drug therapy, compared to a low-fat American Heart Association diet. The Italian researchers also report that the Mediterranean dieters also lost more weight over the first two years of the study.

Investigators suggest that the benefit of the Mediterranean-style diet is due to greater weight loss, olive oil (monunsaturated fats increase insulin sensitivity), and increased adiponectin levels.

The American Diabetes Association recommends both low-carbohydrate and low-fat diets for overweight diabetics. The investigators wondered which of the two might be better, as judged by the need to institute drug therapy in newly diagnosed people with diabetes.

Methodology

Newly diagnosed type 2 diabetics who had never been treated with diabetes drugs were recruited into the study, which was done in Naples, Italy. At the outset, the 215 study participants were 30 to 75 years of age, had body mass index over 25 (average 29.5), had average hemoglobin A1c levels of 7.73, and average glucose levels of 170 mg/dl.

Participants were randomly assigned to one of two diets:

  1. Low-carb Mediterranean diet (“MED diet”, hereafter): rich in vegetables and whole grains, low in red meat (replaced with poultry and fish), no more than 50% of calories from complex carbohydrates, no less than 30% of calories from fat (main source of added fat was 30 to 50 g of olive oil daily). [No mention of fruits. BTW, the traditional Mediterranean diet derives 50-60% of energy from carbohydrates.]
  2. Low-fat diet based on American Heart Association guidelines: rich in whole grains, restricted additional fats/sweets/high-fat snacks, no more than 30% of calories from fat, no more than 10% of calories from saturated fats.

Both diet groups were instructed to limit daily energy intake to 1500 (women) or 1800 (men) calories.

All participants were advised to increase physical activity, mainly walking for at least 30 minutes a day.

Drug therapy was initiated when hemoglobin A1c levels persisted above 7% despite diet and exercise.

The study lasted four years.

Results

By the end of 18 months, twice as many low-fat dieters required diabetes drug therapy compared to the MED dieters—24% versus 12%.

By the end of four years, seven of every 10 low-fat dieters were on drug therapy compared to four of every 10 MED dieters.

The MED dieters lost 2 kg (4.4 lb) more weight by the end of one year, compared to the low-fat group. The groups were no different in net weight loss when measured at four years: down 3–4 kg (7–9 lb).

Compared to the low-fat group, the MED diet cohort achieved significantly lower levels of fasting glucose and hemoglobin A1c throughout the four years.

The MED diet group saw greater increases in insulin sensitivity, i.e., they had less insulin resistance.

The MED group had significantly greater increases in HDL cholesterol and decreases in trigylcerides throughout the study. Total cholesterol decreased more in the MED dieters, but after the first two years the difference from the low-fat group was not significantly different.

Comments

The MED diet here includes “no more than 50% of calories from complex carbohydrates.” The authors don’t define complex carbs. Simple carbohydrates are monosaccharides and disaccharides. Complex carbs are oligosaccharides and polysaccharides. Another definition of complex carbs is “fruits, vegetables, and whole grains,” which I think is definition of complex carbs applicable to this study.

The editors of the Annals of Internal Medicine conclude that:

A low-carbohydrate, Mediterranean-style diet seems to be preferable to a low-fat diet for glycemic control in patients with newly diagnosed type 2 diabetes.

I’m sure the American Diabetes Association will take heed of this study when they next revise their diet guidelines. If I were newly diagnosed with type 2 diabetes, I wouldn’t wait until then.

This study dovetails nicely with others that show prevention of type 2 diabetes with the Mediterranean diet, reversal of metabolic syndrome—a risk factor for diabetes—with the Mediterranean diet (supplemented with nuts), and prevention of type 2 diabetes and pre-diabetes in people who have had a heart attack.

Studies like these support my Low-Carb Mediterranean Diet.

For general information on Mediterranean eating, visit Oldways.

Steve Parker, M.D.

Reference: Esposito, Katherine, et al. Effects of a Mediterranean-style diet on the need for antihyperglycemic drug therapy in patients with newly diagnosed type 2 diabetes. Annals of Internal Medicine, 151 (2009): 306-314.

Low-Carb Diets Killing People?

Animal-based low-carb diets are linked to higher death rates, according to a study in the Annals of Internal Medicine. On the other hand, a vegetable-based low-carb diet was associated with a lower mortality rate, especially from cardiovascular disease.

As always, “association is not causation.”

Since I created the Low-Carb Mediterranean Diet, it’s just a matter of time before someone asks me, “Haven’t you heard that low-carb diets cause premature death?” So I figured I’d better take a close look at the new research by Fung and associates.

It’s pretty weak and unconvincing. I have little to add to the cautious editorial by William Yancy, Matthew Maciejewski, and Kevin Schulman published in the same issue of Annals.

The study at hand was observational over many years, using data from the massive Nurses’ Health Study and Health Professionals’ Follow-up Study. To find the putative differences in mortality, the researchers had to compare the participants eating the most extreme diets. The 80% of study participants eating in between the extremes were neutral in terms of death rates.

They report that “…the overall low-carbohydrate diet score was only weakly associated with all-cause mortality.” Furthermore,

These results suggest that the health effects of a low-carbohydrate diet may depend on the type of protein and fat, and a diet that includes mostly vegetable sources of protein and fat is preferable to a diet with mostly animal sources of protein and fat.

In case you’re wondering, all these low-carb diets derived between 35 and 42% of energy (total calories) from carbohydrate, with an average of 37%. Anecdotally, many committed low-carbers chronically derive 20% of calories from carbohydrate (100 g of carb out of 2,000 calories/day). The average American eats 250 g of carb daily, 50-60% of total calories.

Yancy et al point out that “Fung and coworkers did not show a clear dose-response relationship in that there was not a clear progression of risk moving up or down the diet deciles.” If animal proteins and fats are lethal, you’d expect to see some dose-response relationship, with more deaths as animal consumption gradually increases over the deciles.

The Fung study is suggestive but certainly not definitive. Anyone predisposed to dietary caution who wants to eat lower-carb might benefit from eating fewer animal sources of protein and fat, and more vegetable sources. Fung leaves it entirely up to you to figure out how to do that. Compared to an animal-based low-carb diet, the healthier low-carb diet must subsitute more low-carb vegetables and higher-fat plants like nuts, seeds, seed oils and olive oil, and avocadoes, for example. What are higher-protein plants? Legumes?

You can see how much protein and fat are in your favorite vegetables at the USDA Nutrient Database.

The gist of Fung’s study dovetails with the health benefits linked to low-meat diets such as traditional Mediterranean and DASH. On the other hand, if an animal-based low-carb diet helps keep a bad excess weight problem under control, it too may by healthier than the standard American diet.

See the Yancy editorial for a much more detailed and cogent analysis. As is so often the case, “additional studies are needed.”

Steve Parker, M.D.

Reference: Fung, Teresa, et al. Low-carbohydrate diets and all-cause and cause specific mortality: Two cohort studies. Annals of Internal Medicine, 153 (2010): 289-298.