Diets for Apples and Pears

Summarized by Robert W. Griffith, MD
July 18, 2007

Summary

Overweight apple-shaped persons are high-insulin secretors, while pear-shaped people are low-insulin secretors. The former lose more weight on low-glycemic-load than on low-fat diets, while for the latter there is no great difference between the effects of the two diets.

Introduction

If you're overweight, it's just possible that where your extra weight is carried can help determine which diet is likely to work best for you. We've recently discussed the main types of overweight - see the first link below. The distribution of body fat is used to distinguish two body shapes: gynecoid, or "pear shape", with accumulation of fat in the hips and thighs, vs. android, or "apple shape", with accumulation in the middle part of the body, i.e. the abdomen. (For what its worth, gynecoid means like a woman, and android means like a man.)

The role of insulin, which triggers the body to store excess glucose as fat, is central to the way different food types are handled. Some overweight people secrete high amounts of insulin, others low amounts. The high-secretors are likely to be apple- shaped, the low secretors pear-shaped. A recent study, reported in the Journal of the American Medical Association, has examined the effects of low-glycemic load and low-fat diets in obese young adults, to determine whether insulin secretion affects the weight loss produced. Here's a summary of the findings.

What was done

Researchers at the Children's Hospital in Boston allocated 73 obese adults aged 18 to 35 to take one of two diets for 6 months: either a low-glycemic-load diet (40% carbohydrate, 35% fat, and rich in low glycemic foods) or a low-fat diet (55% carbohydrate, 23% fat). After the 6-month diet phase, the subjects were followed for a further 12 months.

At baseline, all participants had an oral glucose tolerance test in which blood glucose and insulin levels were measured at intervals after a 75 gram dose of glucose. Low-glycemic foods don't produce spikes in blood sugar after eating, so that insulin response spikes are also avoided. Results of the glucose tolerance test allowed the subjects to be categorized as high-insulin or low-insulin secretors, according to whether they were above or below the average insulin level 30 minutes into the glucose tolerance test - 57.5 microgram/mL.

Body weight, body fat percentage determined by dual-energy x-ray absorptiometry (DXR), and standard cardiovascular risk factors were measured at 6, 12, and 18 months from baseline.

What was found

The average age of the participants was 28; 80% were women, and 55% were white. Their average weight was 227 lbs and their body fat percentage 41%.

After 6 months on the diets, the high-insulin secretors ('apples') lost an average of 13 lbs on the low-glycemic diet, and 5 lbs on the low-fat diet. The low-insulin secretors ('pears') lost about 10 lbs on both diets. After 18 months, the high-secretors had lost an average of 12½ lbs on the low-glycemic diet, and 2½ lbs on the low-fat diet; their body fat percentages had fallen by 2.6% and 0.9% on these diets, respectively.

There were no significant differences between the two diets in the low-insulin secretors ('pears'). And, regardless of insulin status, the low-glycemic-load diet improved triglyceride and HDL-cholesterol profiles, whereas the low-fat diet improved LDL- but not HDL-cholesterol or triglyceride levels.

What the findings mean

One should not read too much into the findings in this study. Not enough is known about why high-insulin secretors accumulate fat in their middle section rather than at the pelvis/thigh level. It's safe to advise apple-shaped people to avoid low-fat diets, because the additional carbohydrates they consume may cause more unhealthy spikes in glucose and insulin levels; however, if they can substitute complex (low-glycemic load) carbohydrates like brown rice and oats, they may do well with a low-fat approach.

In short, apple-shaped overweight people will do better with a low-glycemic load diet, while for pear-shaped people it doesn't make too much difference; what's really important is one of the laws of thermodynamics: the only way to really lose weight is to burn more calories than you eat.

Source

• Effects of a low-glycemic load vs low-fat diet in obese young adults. CB. Ebbeling, MM. Leidig, HA. Feldman,  et al. , JAMA, 2007, vol. 297, pp. 2092--2102

Related Links
Your Waist Guidelines
How the Low-Glycemic-Index Diet Works
Waist-Hip Ratio Trumps BMI in Seniors
Dieticians Review Five Popular Diets

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