three diets duke it out

by Diane Lofshult

Food for Thought:

Want to recover more quickly after a hard workout? Stop for a large coffee and whole-wheat bagel on the way home from the gym. That’s the conclusion of a recent report in the Journal of Applied Physiology.

In a randomized clinical trial of trained athletes, researchers examined the effects of a caffeine and carbohydrate mixture—versus carbs alone—on muscle recovery after a bout of exhaustive exercise. Results showed that glycogen, the muscle’s primary fuel during exercise, was replenished more rapidly when athletes ingested the mix of caffeine and carbs as opposed to the carbs alone. When they ingested the combo, athletes had 66% more glycogen in their muscles 4 hours after exercise than they did when they ate only postworkout carbs.

“We provide the first evidence that in trained subjects, the co- ingestion of large amounts of caffeine with carbohydrate has an additive effect on rates of postexercise muscle glycogen accumulation compared to when carbohydrate alone is consumed,” the researchers concluded. Here we go again: a new study has pitted several popular diets against one another, and the media is declaring the diet highest in fat the winner. That’s one way to win friends and influence readership. But, as usual, there is more to the story than fake headlines and easy answers.

The study, which appeared in the July 17 issue of The New England Journal of Medicine, compared three diets: low-fat, restricted-calorie (similar to the Ornish diet); Mediterranean, restricted-calorie; and low-carb, unrestricted-calorie (à la Atkins diet). Over 2 years, the subjects who followed the Mediterranean, restricted-calorie diet lost a mean of 4.4 kilograms (kg), whereas those on the low-fat, restricted-calorie plan lost 2.9 kg. While hailed as the winning diet by many media outlets, the low-carb, unrestricted-calorie group lost a mean of 4.7 kg, only fractionally more than the Mediterranean, restricted-calorie group. And while the low-carb, unrestricted-calorie group did fare best with regard to reducing lipid levels in the blood, the Mediterranean, restricted-calorie diet had it all over the competition when it came to helping with insulin levels and glycemic control in people with diabetes.

Despite the headline banners declaring the Atkins-like diet the winner, the researchers themselves were far more conservative in their conclusions: “Mediterranean and low-carbohydrate diets may be effective alternatives to low-fat diets,” they concluded. “The more favorable effects on lipids (with the low-carbohydrate diet) and on glycemic control (with the Mediterranean diet) suggest that personal preferences and metabolic considerations might inform individualized tailoring of dietary interventions.”

According to Jenna Bell-Wilson, PhD, RD, CSSD, a nutrition consultant and IDEA author and presenter, these findings do not justify adding more fat to your diet, as there were certain flaws in how the research findings were reported in the general media. “First of all, at the 2-year point, all three groups were maintaining a calorie deficit (there was no difference between groups); second, waist circumference and blood pressure improved in all three groups; third, the researchers failed to recognize or report the importance of polyunsaturated fat in the diet, which is important because the Mediterranean diet offers high levels of this healthy form of fat found in nuts and fish.

“The take-home message of this study is that while a low-carb diet may be a safe and effective way to lose weight in the short term, it is more difficult to maintain this food plan in the long term if you want to prevent disease and increase longevity.”