Lots of benefits with avocados, but watch calories

Q. Are avocados really as high-calorie as some people say?

A. Because avocados naturally contain a significant amount of fat, they are indeed much more concentrated in calories than most fruits or vegetables.

Avocados provide heart-healthy fat, however, so they are still a highly nutritious choice when eaten in moderation. But eat a whole avocado by yourself and you may get more than you bargained for. One avocado contains roughly 320 calories -- more than half the number of calories recommended for an average adult meal.

Alternatively, you can enjoy a half-cup of the creamy fruit for 120 calories and still benefit from 5 grams of dietary fiber and more than 10 percent of the Recommended Daily Values for potassium and folate.

Q. Does eating more fiber improve weight loss?

A. Including more high-fiber foods in your diet seems to be a good strategy for both weight maintenance and weight loss.

Soluble fiber in particular (found in oats, beans, fruits and some vegetables) helps delay digestion as well as the ensuing rise in blood sugar and insulin after eating carbohydrates; these factors could affect hunger and metabolism.

But experts aren't completely sure how much of the benefit can be attributed to fiber itself. Other factors may be at play.

For example, research suggests that increasing dietary fiber may help reduce calorie consumption in general by making diners feel more full. Similarly, the latest American Institute for Cancer Research report on diet and cancer risk notes that high-fiber foods likely support weight control because they are low in energy density (i.e., not very concentrated in calories).

When eating a diet rich in vegetables, fruits, beans and whole grains -- four fiber all-stars -- you can easily satisfy your hunger without tipping the calorie scales. In other words, supplementing an unhealthy diet with fiber pills or high-fiber yet high-calorie foods is unlikely to promote weight loss. But substituting more filling, fiber-rich foods for less healthy foods may.

Q. Is it true that vinegar helps control blood sugar?

A. Reducing large spikes in blood sugar is an important step in preventing organ damage from diabetes and likely reducing the development of insulin resistance. Evidence from at least six small studies in the last decade suggests that vinegar may improve blood sugar control in certain situations.

On average, the studies showed that people who consumed about two or three teaspoons of white or cider vinegar with a high-carbohydrate meal had lower blood sugar levels (from 20 to 55 percent lower) than when they ate a similar meal without vinegar.

Researchers suggest that the acetic acid in vinegar may decrease the activity of one of the enzymes central to carbohydrate digestion, thus slowing the release of glucose into the blood stream. Some earlier research suggested that acetic acid might also delay stomach emptying.

Either way, these findings could provide an extra incentive to include a salad with a vinegar-based dressing (or other foods containing vinegar) alongside a meal that is particularly carb-heavy.

Medicinal use of vinegar is not recommended. Because it appears to work only when consumed with a high-carbohydrate meal, vinegar should not be taken to reduce blood sugars that are already elevated.

Many blood sugar problems are due to weight and lack of physical activity. Don't try to make up for overeating with a simple dose of vinegar. In the end, your greatest ally in blood sugar control is a healthy lifestyle.