Treatment-Weight loss

The main treatment for obesity is to reduce body fat by eating fewer calories and exercising more. A beneficial side effect of exercise is to increase muscle, tendon, and ligament strength, which helps to prevent injury from accidents and vigorous activity. Diet and exercise programs produce an average weight loss of approximately 8% of total body mass (excluding program drop-outs). Not all dieters are satisfied with these results, but a loss of as little as 5% of body mass can create large health benefits.[citation needed]

Much more difficult than reducing body fat is keeping it off. Eighty to ninety-five percent of those who lose 10% or more of their body mass by dieting regain all that weight back within two to five years. The body has systems that maintain its homeostasis at certain set points, including body weight.[citation needed] Therefore, keeping weight off generally requires making exercise and eating right a permanent part of a person's lifestyle. Certain nutrients, such as phenylalanine, are natural appetite suppressants which allow resetting of the body's set point for body weight.[citation needed]

Clinical protocols

In a clinical practice guideline by the American College of Physicians, the following five recommendations are made:[33]
People with a BMI of over 30 should be counseled on diet, exercise and other relevant behavioral interventions, and set a realistic goal for weight loss.
If these goals are not achieved, pharmacotherapy can be offered. The patient needs to be informed of the possibility of side-effects and the unavailability of long-term safety and efficacy data.
Drug therapy may consist of sibutramine, orlistat, phentermine, diethylpropion, fluoxetine, and bupropion. For more severe cases of obesity, stronger drugs such as amphetamine and methamphetamine may be used on a selective basis. Evidence is not sufficient to recommend sertraline, topiramate, or zonisamide.
In patients with BMI > 40 who fail to achieve their weight loss goals (with or without medication) and who develop obesity-related complications, referral for bariatric surgery may be indicated. The patient needs to be aware of the potential complications.
Those requiring bariatric surgery should be referred to high-volume referral centers, as the evidence suggests that surgeons who frequently perform these procedures have fewer complications.

A clinical practice guideline by the US Preventive Services Task Force (USPSTF) concluded that the evidence is insufficient to recommend for or against routine behavioral counseling to promote a healthy diet in unselected patients in primary care settings, but that intensive behavioral dietary counseling is recommended in those with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. Intensive counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians.[34][35]

Exercise

Exercise requires energy (calories). Calories are stored in body fat. The body breaks down its fat stores in order to provide energy during prolonged aerobic exercise. The largest muscles in the body are the leg muscles, and naturally these burn the most calories, which make walking, running, and cycling among the most effective forms of exercise for reducing body fat.

A meta-analysis of randomized controlled trials by the international Cochrane Collaboration found that "exercise combined with diet resulted in a greater weight reduction than diet alone".[36]

Dieting
Main article: Dieting

In general, dieting means eating less. Various dietary approaches have been proposed, some of which have been compared by randomized controlled trials:
A comparison of Dr. Atkins', Slim-Fast's, Weight Watchers', and Rosemary Conley's diets found no significant differences.[37]
A comparison of Atkins diet, Zone diet, Weight Watchers, and Ornish diet noted:[38]
"all 4 diets resulted in modest statistically significant weight loss at 1 year, with no statistically significant differences between diets"
"The higher discontinuation rates for the Atkins and Ornish diet groups suggest many individuals found these diets to be too extreme"

Low carbohydrate versus low fat
Main article: Medical research related to low-carbohydrate diets

Many studies have focused on diets that reduce calories via a low-carbohydrate (Atkins diet, Zone diet) diet versus a low-fat diet (LEARN diet, Ornish diet). The Nurses' Health Study, an observational cohort study, found that low carbohydrate diets based on vegetable sources of fat and protein are associated with less coronary heart disease.[39]

A meta-analysis of randomized controlled trials by the international Cochrane Collaboration in 2002 concluded[40] that fat-restricted diets are no better than calorie restricted diets in achieving long term weight loss in overweight or obese people.

A more recent meta-analysis that included randomized controlled trials published after the Cochrane review[41][42][38] found that "low-carbohydrate, non-energy-restricted diets appear to be at least as effective as low-fat, energy-restricted diets in inducing weight loss for up to 1 year. However, potential favorable changes in triglyceride and high-density lipoprotein cholesterol values should be weighed against potential unfavorable changes in low-density lipoprotein cholesterol values when low-carbohydrate diets to induce weight loss are considered."[43]

The Women's Health Initiative Randomized Controlled Dietary Modification Trial[44] found that a diet of total fat to 20% of energy and increasing consumption of vegetables and fruit to at least 5 servings daily and grains to at least 6 servings daily resulted in:
no reduction in cardiovascular disease[45]
an insignificant reduction in invasive breast cancer[46]
no reductions in colorectal cancer[47]

Additional recent randomized controlled trials have found that:
A comparison of Atkins, Zone diet, Ornish diet, and LEARN diet in premenopausal women found the greatest benefit from the Atkins diet.[48]
The choice of diet for a specific person may be influenced by measuring the invididual's insulin secretion:
In young adults "Reducing glycemic [carbohydrate] load may be especially important to achieve weight loss among individuals with high insulin secretion."[49] This is consistent with prior studies of diabetic patients in which low carbohydrate diets were more beneficial.[50][51]

The American Diabetes Association released for the first time a recommendation for a low carbohydrate diet to reduce weight for those with or at risk of Type 2 diabetes. The American Diabetes Association released its 2008 Clinical Practice Recommendations for physicians in January 20