Consider the criteria discussed below in evaluating whether popular diets are likely to contribute to safe and effective weight control. General categories of weight-reducing diets are shown in Table 97.1. Start by calculating a rough estimate of energy needs, using the approximation shown in Table 97.2.
The calorie deficit approach involves active involvement on the part of the dieter in decreasing usual food intake. Energy deficits of 500 calories per day from energy balance levels (calculated as in Table 97.2) will cause a loss of about 1 pound of fat tissue per week. To lose 10 pounds, at least 10 weeks with perfect adherence will be needed. Deficits greater than 500 calories are not recommended for self-initiated efforts.
Many diets for weight reduction use fixed calorie levels that limit intake by controlling portion sizes, food composition, menus, choices, and spontaneity in dietary selection. Some people find such eating plans easier to adhere to than the calorie deficit approach. Popular diets of this type include reducing regimens in many diet books and fixed lowcalorie diet programs operated by commercial and nonprofit weight loss management groups (see Chapters 95 and 98). They often use prepackaged and portion controlled foods such as low-calorie frozen and canned entrees, and other products available in supermarkets. Common energy levels of such diets range from about 1,200–1,800 kcals, but the problem is that they are often not individualized.