The most important aspect of any diet to prevent type 2 diabetes is its calorie (i.e., energy) content. If calorie intake exceeds calorie usage, then the excess calories will, in the absence of other modifying factors, be directed toward the body’s energy storage compartment, which is, of course, the fat tissue. Therefore, a diet that matches calorie consumption with output is the key to prevention of overweight and obesity and therefore diabetes. If one is already overweight, then the diet should provide fewer calories than are required, so that energy will be drawn from the body fat stores and gradual weight loss will occur. Even modest weight loss can be very beneficial.
The benefits can be shown very early, almost as soon as calorie intake drops below that required to maintain body weight and before significant weight loss actually occurs. The consumption side of this balance is, of course, food intake. The output side that we can control is exercise. Neither can operate successfully to regulate weight independent of the other. Very calorie-dense foods, such as those with a high fat content (e.g., cheese, ice cream, fried foods, and processed meats) are common components of diets that lead to weight gain, obesity, and ultimately diabetes. Although sugar itself does not cause diabetes, foods with a high content of refined sugar, such as sodas and candies, are also more likely to be associated with weight gain and diabetes than those with natural sugars. Natural sugars tend to be associated with fiber, which delays and limits their absorption.
Thus, portion for portion, more sugar is consumed in foods high in refined sugar. The question of whether a specific diet composition can prevent diabetes, independent of its actual energy content, is not entirely known. Studies have shown that diets high in grain and fiber tend to be associated with a lower frequency of diabetes in the population. This may be related to the more gradual breakdown and absorption of the components of the meal, especially the carbohydrates, as discussed previously. Since, in all parts of the world, the explosive rise in diabetes is clearly linked to weight gain (with some population groups being more susceptible than others) rather than to a specific type of diet, the dietary focus should remain on eating a healthy diet that provides the recommended amounts of important nutrients, in quantities necessary to maintain a healthy weight and prevent undesirable weight gain.