Lifestyle Modifications -Diet Recommendations-
A substantial contribution to the obesity and overweight epidemic in both Western and developing countries has been given by the increase in the consumption, during growth as well as in adulthood, of foods with high energy density and low nutritional value (foods with visible fats, soft drinks with caloric sweeteners, snacks, sweets) and the strong reduction of physical activity at work and during leisure time.
The nonpharmacological treatment for overweight and obesity needs to modify unhealthy dietary habits and encourage physical activity, according to the patient’s clinical conditions: in other words, a physical and nutritional rehabilitative program is often required. Moreover, an adequate integrative intervention enhances the effectiveness of the single components and optimizes the use of drugs for comorbidities; in fact, there is a well-known effective interaction between diet and physical exercise.
Treatments to correct obesity aim to reduce initial body weight – in particular for grades I and II obesity or in case of overweight – within 4–6 months. Only in case of grade III obesity it is necessary to lose more than the conventional amount of 10 %.
In substance, it has been observed that a stable loss of 10 % of the initial body weight, achieved by losing mainly fat tissue, is adequate to correct the risk of obesity- linked morbidities.
The nutritional intervention, in both public and private institutions, must never disregard a simple but thorough dietary education. When eating disorders linked with a personality disturbance are present, a psychotherapeutic clinic and diagnostic intervention is also indicated.
Carbohydrates
Carbohydrates should represent 50–55 % of total calories; fiber-enriched foods and slow absorption starch should be preferred, limiting the amount of energy from simple sugars. (Level of evidence I, Strength of recommendation A )
Cereals, fruits, and vegetables are important components of a healthy diet and have to be taken in consideration in a regimen for obesity. ( Level of evidence I , Strength of recommendation A )
Glycemic Index
The glycemic index of a food indicates the increase in blood glucose levels after the consumption of a food containing 50 g carbohydrates. This is influenced above all by the quality of carbohydrates (the simpler they are, the higher is the glycemic index) and by some characteristics of the meal, such as type of cooking, presence of fibers and interaction with fats and proteins.
The glycemic index needs to be considered in selecting food for the daily diet. In particular, foods with a low glycemic index have to be preferred to maintain body weight during a low-calorie diet
Proteins
The recommended daily protein intake in adults should be 0.8–1.0 g/kg desirable weight (i.e., weight corresponding to 22.5–25 kg/m 2 BMI). Similarly, for developmental age, national nutritional recommendations should be followed.
proteins should derive both from animal and vegetal protein sources.
Fats
A well-balanced diet should contain less than 30 % lipids of the daily energy intake, with an optimal intake of 10 % MUFA, 10 % PUFA, 10 % saturated fatty acids.
Daily intake of cholesterol should not exceed 300 mg/day in adults and 100 mg/1000 kcal (4190 kJ) in developmental age.
The introduction of at least two servings of fish weekly is recommended to supply n3 polyunsaturated fatty acids, with benefits on the prevention of cardiovascular risks.
The use of trans fatty acids has to be strongly reduced because it is associated with body weight, waist circumference, and BMI increase in population studies. It is recommended not to exceed 2.5 g/day of trans fatty acids in relation to cardiovascular risks.
Fiber
Dietary fiber has functional and metabolic effects. Beyond satiation and the improvement of intestinal functions, dietary fiber reduces the risk of chronic-degenerative diseases (diabetes, cardiovascular diseases) and some gastrointestinal neoplasms.
In adults, the intake of at least 30 g/day of vegetal fiber is recommended and the supplement of vegetal fibers during caloric restriction is effective to improve metabolic parameters. ( Level of evidence I , Strength of recommendation A )
Alcohol
Given its metabolic characteristics and the readily available calories it provides, alcohol is not recommended during a weight loss regimen since it limits the utilization of other nutrients and has no satiating power. ( Level of evidence I , Strength of recommendation B )
Alcohol could be reintroduced in a “weight-maintenance” regimen once the patient has reached adequate weight; it should be consumed in limited doses and counted in the total daily calories prescribed
Sweet Drinks
Sweetened drinks are not recommended because, as they add extra calories, they negatively infl uence both satiety and satiation. The patient needs to be informed about their negative effects on body weight. The consumption of sweetened drinks has to be controlled, particularly during pediatric age, because they r epresent a source of “empty” calories, nowadays scarcely considered by subjects with overweight/obesity and their families. ( Level of evidence I, Strength of recommendation A)
Sucrose and Other Added Sugars
The intake of foods containing sucrose and other added sugars should be balanced with the intake of other carbohydrates, in order to avoid exceeding the total daily calorie intake.
The excessive habitual consumption of sucrose and other added sugars could cause weight increase, insulin resistance and higher triacylglycerol blood levels. ( Level of evidence I , Strength of recommendation A )
Special Foods, Nutritional Supplements, Noncaloric Sweeteners
Generally, there is no indication to use special foods, whether precooked or packaged. The same is true for vitamin and mineral supplements, which should be given only to patients presenting a diet history with clear nutritional deficiencies. The use of noncaloric sweeteners is controversial because they may impair both satiety and satiation.
Mediterranean Diet
The Mediterranean Diet is not correlated with an increased risk of overweight and obesity and could play a role in the prevention of both. Long-term intervention studies are required to prove the effectiveness of a Mediterranean type of diet in promoting and preventing overweight and obesity. ( Level of evidence I , Strength of recommendation B )
The adhesion to a typical Mediterranean Diet has favorable effects on mortality for cardiovascular diseases and cancer and on the incidence of Parkinson’s and Alzheimer’s diseases; it therefore could play a protective role on the primary prevention of chronic-degenerative diseases. ( Level of evidence I , Strength of recommendation B )
Dietary Recommendations in Some Clinical Conditions
- Diet Therapy of Obesity in Adolescence
There are no specific indications other than to empower educational programs toward healthy diet and lifestyle; regular physical exercise, and an adequate intake of proteins, minerals, and vitamins through the consumption of a large variety of natural foods, should be encouraged and stimulated.
- Diet Therapy for Obesity during Pregnancy and Lactation
During pregnancy, it is sufficient to guarantee an adequate supply of proteins and foods rich in high bioavailable calcium (partially skimmed milk, yogurt, water). In particular, in the third trimester, the prescription of a diet with a caloric supply of at least 1600 kcal (6704 kJ)/day is suggested. During lactation, a woman who was overweight/obese before pregnancy could start a weight-reducing diet and try to attain a normal BMI. The energy cost for milk production is about 500–600 kcal/ day for the first 6 months of exclusive breastfeeding. For this reason and in consideration of the energy saving due to the physiological weight loss following pregnancy, national recommendations usually suggest a supply of about 500 kcal/day for a healthy woman. In overweight/obese lactating mothers, it will be sufficient to maintain a calorie supply corresponding to the real needs, without adjusting for ideal weight, since this supply will be in any case 500 kcal lower than necessary.
Particular attention is required to satisfy the increased needs in micronutrients and vitamins for milk production.
Grade III Obesity
In this case, the suggested energy intake is 1000 kcal (4190 kJ) lower than the habitual diet, with close evaluation by an expert dietitian, which includes a dietary assessment and follow-up, with special attention to pharmacological therapy of possible complications; the surgical option, in case of medical failure, has to be considered and proposed by a specialized team.
Finally, diet is a nonpharmacological therapy: it is a therapeutic intervention and has to be prescribed by physicians and elaborated by specialized personnel (dietician).
Specific Recommendations
W eight loss is suggested also for people with BMI between 25 and 28, in the presence of complications or personal history of diseases linked to excess body fat and in case of sarcopenia (altered fat-free/fat mass ratio): in these conditions, body weight correction has to be achieved exclusively by nonpharmacological therapy and physical rehabilitation.
Dietary restriction has to be evaluated according to the patient’s energy expenditure, preferably measured (resting energy expenditure measured with indirect calorimetry in standard conditions or calculated by predictive formulas – Harris-Benedict’s or WHO – and multiplied by 1.3). Generally, an energy restriction of 500–1000 kcal (2095–4190 kJ) is suggested, compared to the daily energy expenditure. Low- calorie diets with a daily caloric intake lower than 1300 kcal (5447 kJ)/day should not be prescribed to outpatients.
Diet composition should guarantee an adequate protein/nonprotein calorie ratio: the lower nonprotein calories are, the higher protein calories should be. Generally, proteins should derive from both animal and vegetal origin: 0.8–1 g proteins/kg desirable body weight is suggested (only rarely up to 1.3–1.5 g/kg desirable weight). Desirable weight corresponds to 22–25 kg/m 2 Body Mass Index calculated for the patient’s squared height. As far as nonprotein calories, the amount of carbohydrates should derive from foods with low glycemic index, and fats should be of vegetal origin (limiting coconut and palm oil) and used above all for seasoning. Extra virgin olive oil should be preferred. It is advisable not to limit carbohydrate intake below 120–130 g/day and fats below 20–25 g/day.
Suggested food items are preferably vegetables, as in the Mediterranean food model: cereals, legumes, vegetables, and fruit as source of carbohydrates and a percentage of dietary proteins, lean meats, and fish (at least two–three times a week) as animal proteins, extra virgin olive oil as seasoning fat. Regular milk, yoghurt, and low-fat dairy products have to be guaranteed to ensure the protein and the calcium supply.
As to meal distribution, it is appropriate to suggest a relatively abundant breakfast (partially skimmed milk, cereals, fruits, yoghurt) and a light dinner early in the evening. A light breakfast and evening meal have no specific indications to correct obesity except for given metabolic diseases or individual requests.
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