People with Type 2 diabetes are advised to limit carbohydrates because of worries that too many carbs could overtax the body's dwindling insulin production and lessen its ability to process glucose.

Now some scientists are asking if a very-low-fat diet rich in healthy carbohydrates -- whole grains, beans, fruit and vegetables -- might be another option.

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The idea borrows a lesson from the heart disease field, which has shown that very strict vegetarian diets quite low in fat and very high in carbohydrates can help reverse arterial blockages. Such diets have proven very difficult to stick with, absent high motivation and plenty of support.

"A diet can be wonderful for you, but if it can't be practically applied, it can't do much," notes American Heart Association president Robert Eckel.

In May, physician Dean Ornish, a proponent of the very-low-fat approach for reversing heart disease, reported that this regimen also helped a subset of people with both diabetes and heart disease.

In the study, published in the American Journal of Cardiology, participants who followed the approach shed pounds. Blood levels of low-density lipoprotein (LDL), "bad" cholesterol that raises heart disease risk, dropped. Levels of protective high-density lipoprotein (HDL) didn't drop, and unhealthy fats known as triglycerides didn't rise, as some researchers had feared. Another key finding: 20 percent of participants who stuck with the diet for a year were able to cut or eliminate their insulin and other glucose-lowering medications.

Similar results are expected later this week from a study headed by the University of Toronto's David Jenkins and Neal Barnard of the Physicians Committee for Responsible Medicine, a pro-vegetarian group.

The four-month trial, funded by the National Institutes of Health, studied 99 people with Type 2 diabetes. Half were asked to follow the standard dietary advice from the American Diabetes Association (ADA). The other half were asked to adhere to a very strict, low-fat vegan diet devoid of meat, fish, eggs, dairy or any other animal products.

Both groups improved blood sugar control and LDL cholesterol levels. Both lost weight, but the vegan group shed an average of 15 pounds, compared with six for the ADA group. As in the Ornish study, the vegan group showed no harmful changes in either HDL or triglyceride levels. Results of the study are scheduled to be published Thursday in the journal Diabetes Care.

Learning to go vegan takes effort, time and some sacrifice, however. Vance Warren, 36, a retired District police officer, learned this while participating in the study.

"I know the difference between a Morton's steak and a tofu steak," says Warren, who lost more than 70 pounds during the study and reduced the medication he must take to control his blood sugar. "It's like the difference between a Mercedes and a Toyota. The hardest thing for me was giving up the chicken wings . . . but I really don't miss them now."

Experts caution that none of these findings are likely to change current dietary recommendations until much more study is done with larger groups of people.

"It's great that the low-fat vegan diet improved glycemic [blood sugar] control," notes Karmeen Kulkarni, vice president of health care and education for the ADA. "But we had 50 people here. We have to see if this is palatable in a bigger scheme of things on an ongoing basis."

Until that research is completed, there's wide agreement from many expert groups on what constitutes a healthy diet for people with diabetes -- or those trying to prevent it and other health problems, including heart disease and cancer:

Eat more plant-based foods . The more variety, the better. Groups that recommend eating more beans, vegetables (without added fat), fruit (sans added sugar) and whole grains include the American Heart Association, the National Cancer Institute, the Institute of Medicine, the National Heart, Lung, and Blood Institute, the American Diabetes Association, the American Cancer Society and the American Institute for Cancer Research.

Easy on the fat . Gram for gram, fat contains more than twice the calories of protein or carbs. Being overweight or obese is a major risk factor for diabetes, heart disease and some types of cancer. Whatever fat you eat, make it healthy. Skip saturated fat, trans fat and cholesterol found in whole milk dairy products, fatty meat and poultry with the skin. Reach instead for fish, healthy oil such as canola or olive oil, healthy margarine, nuts, avocados and seeds.

Get plenty of exercise . The Diabetes Prevention Program -- a large federally funded study of people who were just a step shy of developing diabetes -- found that brisk daily exercise (yes, walking is fine) played an important part in preventing diabetes. The study found 30 minutes daily was required, but that can be broken into 10-minute increments. ?

Join Sally Squires, author of "Secrets of the Lean Plate Club" (St. Martin's Press) online today from 1 p.m. to 2 p.m. at www.washingtonpost.com/leanplatelub, where you can also find some vegan recipes used in the study and subscribe to the free Lean Plate Club e-mail newsletter.