Focus: Four Plans for Weight Loss; Garlic for LDL Cholesterol
Comparing Four Weight-Loss Plans
© iStockphoto.com/Julie de Leseleuc
The Atkins diet, a very-low-carbohydrate diet, may contribute to greater weight loss than higher carbohydrate plans, without negative effects such as increased cholesterol, Dr. Christopher Gardner and his colleagues have found (see Perspective). The NCCAM-funded study was conducted in 311 premenopausal women, all of whom were overweight or obese. Each woman was randomly assigned to one of four diets. All diets had been selected for their different levels of carbohydrate consumption:
- The Atkins diet is very low in carbohydrate consumption: less than 20 grams of carbohydrates per day and increasing to 50 grams per day.
- The Zone diet is designed so that a person's daily calorie consumption is made up of 40 percent carbohydrates, 30 percent protein, and 30 percent fat.
- The LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition) diet instructs participants to get 55 to 60 percent of their calories from carbohydrates and not more than 10 percent from saturated fat. It is based on the U.S. Department of Agriculture food pyramid.
- The Ornish diet's primary guideline states that participants should not get more than 10 percent of their calories from fat.
All participants received books accompanying their assigned diet plan and attended hour-long classes with a registered dietician once a week for the first 8 weeks. Data on the participants was collected at the beginning of the study and at 2, 6, and 12 months. The researchers recorded body mass index (BMI); body fat percentage; waist-hip ratio; and metabolic measures such as insulin, cholesterol, glucose, triglyceride, and blood pressure levels.
The Atkins group reported the most weight loss at 12 months, with an average loss of just over 10 pounds (4.7 kilograms). They also had more favorable overall metabolic effects. Average weight loss across all four groups ranged from 3.5 to 10.4 pounds. The authors note that "even modest reductions in excess weight have clinically significant effects on risk factors such as triglycerides and blood pressure."
Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women. The A to Z Weight Loss Study: a randomized trial. Journal of the American Medical Association. 2007;297(9):969-977.
Garlic and "Bad" Cholesterol
© Steven Foster
LDL (low-density lipoprotein) cholesterol is widely known as "bad cholesterol" and is believed to be a leading contributor to heart disease. This study's results cast doubt on garlic's effectiveness in lowering LDL cholesterol levels in adults with moderately high cholesterol.
Dr. Gardner and his team conducted a randomized, placebo-controlled trial studying whether three different formulations of garlic could lower LDL cholesterol. The study participants were randomly divided into four groups to receive either raw garlic, a powdered garlic supplement, an aged extract supplement, or a placebo.
The 169 participants who completed the study had their cholesterol levels checked monthly during the 6-month trial. None of the formulations of garlic had a statistically significant effect on the LDL cholesterol levels. The authors caution that their results should not be generalized for all populations or all health effects. An accompanying editorial in the journal points out that LDL cholesterol levels are only one factor contributing to heart disease and that this trial did not investigate garlic's effects on other risk factors, such as high blood pressure.
Gardner CD, Lawson LD, Block E, et al. Effect of raw garlic vs. commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial. Archives of Internal Medicine. 2007;167(4):346-353.
