People are encouraged to eat more fruit and vegetables to improve their general health and increase life expectancy. But until recently there was no reliable information about which fruits and vegetables are better for people trying to lose weight.
Does variations in dietary fiber and the glycemic load (GL) make a difference?
A very large study involving more than 70 fruits and vegetables and over 130,000 American and women has provided some answers. The volunteers for the study provided details of their weight and diet at 4-year intervals for up to 24 years.
Fruits and vegetables were grouped as having:
► high or low fiber
► high or low Glycemic Load, which was calculated by multiplying the carbohydrate in each fruit and vegetable by the glycemic index for that item.
Fruits were categorized into:
Vegetables were classified into:
► cruciferous vegetables: cauliflower, cabbage, garden cress, bok choy, broccoli, Brussels sprouts and other members of the Brassicaceae Family,
► green leafy vegetables
The classification was based on similarity of nutritional content.
Adjustments were made for lifestyle variables, including smoking status, physical activity level, daily hours of inactivity (sitting) and hours of sleep.
The conclusions from the study were:
► As expected starchy vegetables such as potatoes, and pumpkin was linked to to weight gain
► Eating an extra piece of fruit a day produced a weight loss of 0.5 lb or 0.24 kg, so two extra fruit portions a day lead to a weight loss of 1 lb. Eating 4 extra pieces of fruit a day produced a weight loss of 2 lb or 1 kg.
► The best fruits were berries, apples and pears.
► The most effective fruits from best to worst (see the image) were:
► Eating an extra daily portion of vegetables was only about half as effective. Eating and extra serving of vegetables produced a weight loss of 0.25 lb or 0.11 kg. So eating an extra 4 pieces of vegetables produced a weight loss of 1 lb or 0.5 kg.
► The highest weight loss occurred for lower-glycemic vegetables rich in fiber. Cruciferous vegetables, such as Brussels sprouts, broccoli and cauliflower were most effective.
► For vegetables, weight gain was associated with eating higher-glycemic, lower-fiber and starchy vegetables. Examples of these vegetables were potatoes, corn, peas, cabbage and carrots.
► While weight changes appear to be small, eating and extra 2-4 portions of BOTH fruits and vegetables could be very effective long term, especially when combined with reducing calorie intakes, portion sizes at mealtimes and increased activity.
► Eating extra servings of berries, daily, was associated with an average 1.1 pound reduction in weight gained; apples and pears 1.2 pounds with less weight gained, but citrus fruits only showed a 0.3 pound lower gain over 4 years.
► Adding an extra daily serving of tofu or soy to the diet was associated with about 2.5 pounds less weight gained
► Eating extra servings of carrots and peppers were associated with small reductions in weight gains, but potatoes, peas and corn were not, and were associated with weight increases over 4 years.