We have just considered the gravity of the obesity problem.  This section explores various weight-loss strategies and the effectiveness of each. Successful weight loss is when a person intentionally loses at least 10 percent of their body weight and keeps it off for at least a year. ^[1]  Studies suggest that most of us are not successful.  A large-scale study involving more than 14,000 adults found that only one in six overweight or obese individuals was able to lose weight and keep it off for one year.  ^[2]This raises the question: Why is achieving long-term weight loss so difficult? Much of the explanation lies in understanding the biology of weight loss.

Biology of Weight Loss

As discussed earlier,  if you eat more calories than you burn, you gain weight. If you burn more calories than you eat, you lose weight. This general formula of energy balance provides the foundation for the basic premise of weight management.

However, the body is more complex than a simple formula. And, as with other functions within the body, weight is tightly regulated. To prevent perpetual weight loss or gain, our bodies strive to maintain a stable weight. But our obesogenic environment often promotes behaviors that encourage excessive caloric intake and lower energy expenditure, leading to weight gain over time.

At the start of a weight-loss diet, we typically lose weight rapidly. But the same mechanisms that help maintain a steady weight also kick in during periods of weight loss to help us return to our original weight.  ^[3]The body recognizes weight loss as a threat to survival, lowering basal metabolic rate to preserve calories and protect against starvation. Additionally, as body weight decreases,  we need less energy to carry our lighter body weight.   This results in fewer calories burned through physical activity.

Biological differences in individual metabolism may also affect weight-loss success. Researchers have found that some individuals have a “thrifty” metabolism, meaning that they have a lower metabolic rate.  These thrifty individuals expend fewer calories when in a fasting (or calorie-restricted) state, a common state in weight-loss efforts. This results in lower weight loss. In contrast, individuals with a “spendthrift” metabolism tend to have a higher metabolic rate in a fasting state, burning more calories and thus making weight loss easier. ^[4] According to researcher Martin Reinhardt, “The results corroborate the idea that some people who are obese may have to work harder to lose weight due to metabolic differences.” ^[5]

Research also suggests that changes in hormone levels from weight loss may affect the body’s ability to maintain weight loss.  Thyroid hormone levels decrease, which lowers the metabolic rate. As fat cells decline, leptin levels also decline, increasing appetite and decreasing metabolic rate. These hormonal changes result in the need for fewer calories and make keeping the weight off difficult.  ^[6]  These biological factors and their influence on weight are discussed further in the video below.

Components of Weight Loss Program

Evidence shows that successful weight loss and long-term weight maintenance are possible, even with the body’s natural biological adaptations that can make weight loss challenging. Because individuals differ in their preferences, health status, and environment, no single approach works for everyone.

However, most effective weight management strategies include three key components:

• Reducing calorie intake, particularly from foods high in fat and added sugars
• Increasing physical activity to support energy balance and overall health
• Using behavioral strategies, such as goal setting, self-monitoring, and building sustainable habits

Dietary Considerations for Weight Loss

Although following a lower-calorie healthy eating plan is often the first approach to weight loss, research shows that no single dietary strategy is superior to others.^9,10   For example, a recent trial, called the DIETFITS study, followed participants on either a low-fat or a low-carbohydrate diet for 1 year and found no significant difference in weight loss between the groups. ^[7]  Both dietary strategies produced a range of weight loss results. Some participants lost more than 60 pounds, while others gained 20 pounds over the year, suggesting that what works for one individual may have varying effects on others.

To learn more about the DIETFITS study, check out the following video.

National Weight Control Registry

The National Weight Control Registry (NWCR) has tracked more than 10,000 people who have successfully lost 30 pounds and maintained this weight loss for at least one year. Their research findings show that 98 percent of participants in the registry modified their food intake, and 94 percent increased their physical activity, mainly by walking. ^[8]

There was a wide variety of approaches NWCR members used to achieve successful weight loss. Most involved a low-calorie, low-fat diet while exercising. (Most got one hour of exercise per day.) Moreover, most members eat breakfast every day, watch fewer than ten hours of television per week, and weigh themselves at least once per week. About half of them lost weight independently, and the other half used a weight-loss program.

In most scientific studies, successful weight loss is accomplished only by changing the diet while increasing physical activity. Doing one without the other limits the amount of weight loss and the duration of sustained weight loss. ^[9]

Dietary Recommendations for Weight Loss

The 2025–2030 Dietary Guidelines for Americans provide evidence-based recommendations to support overall health and help maintain a healthy body weight. Like previous editions, they emphasize achieving energy balance—matching calorie intake with physical activity—and adopting sustainable eating patterns that can be maintained over time.

A healthy dietary pattern includes:

• A variety of vegetables from all subgroups, including dark green, red and orange, legumes (beans and peas), and starchy vegetables
• Fruits, especially whole fruits
• Grains, with at least half coming from whole grains
• Dairy foods,  including fat-free or low-fat dairy such as milk and yogurt
• A variety of protein foods, such as seafood, lean meats and poultry, eggs, legumes, nuts, seeds, and soy products

The guidelines also recommend limiting components that are linked to chronic disease risk:

• Added sugars: less than 10% of total daily calories
• Saturated fats: less than 10% of total daily calories
• Sodium: less than 2,300 mg per day
• Alcohol: if consumed, limit to one drink per day for women and two drinks per day for men, and only for adults of legal drinking age

Typical Dietary Intakes of Americans

While these guidelines establish basic dietary intake recommendations across all food groups, most Americans do not meet them. Figure 7.29 shows that Americans are falling short of the recommendations for vegetables, fruit, whole grains, dairy, and seafood, and consume well over the recommended amount of refined grains. Meanwhile, many Americans also exceed the recommended limits for added sugars, saturated fats, sodium, and alcohol. As recommended in the Dietary Guidelines, shifting towards more nutrient-dense choices would help balance caloric intake and meet nutrient needs for optimal health.

Physical Activity Recommendations For Weight Loss

Physical activity is a vital part of losing weight and keeping it off. The 2018 Physical Activity Guidelines for Americans provide recommendations to Americans aged 3 and older on improving health and reducing chronic disease risk through physical activity. Increased physical activity lowers the risk of heart disease, stroke, high blood pressure, Type 2 diabetes, colon, breast, lung cancer, falls and fractures, depression, and early death. Increased physical activity not only reduces disease risk but also improves overall health. Benefits include enhancing cardiovascular and muscular fitness, increasing bone density and strength, improving cognitive function, and losing weight and keeping it off.  ^[10]

 Moderate vs. Vigorous Activity

The 2018 Physical Activity Guidelines broadly classify moderate physical activities as those when you “can talk, but not sing, during the activity” and vigorous activities as those when you “cannot say more than a few words without pausing for a breath.”  ^[11]  Despite the indisputable benefits of regular physical activity, a 2022report from the American Heart Association estimates that 8 out of 10 Americans do not meet these guidelines. ^[12]
 

Given the number of Americans who are falling short on both nutrition and physical activity recommendations, it is easy to see that these two areas of behavior are of primary interest in improving the health and weight of our nation.

Behavioral Strategies for Weight Management

Behavioral Health Team

The behavioral health team often includes primary care clinicians, dietitians, psychologists, behavioral therapists, exercise physiologists, and lifestyle coaches. These programs may consist of various delivery methods, often through group classes of 10-20 participants. The classes may be in-person or online courses and often use print and digital materials. The interventions usually span one to two years, with more frequent contact in the initial months (weekly to bi-monthly) followed by less regular contact (monthly) in the latter months or maintenance phase.  A variety of behavioral topics is covered throughout the program, ranging from nutrition education and goal-setting to problem-solving and assertiveness. Relapse prevention is a part of the maintenance phase. ^[14]

Medically Prescribed Treatments

In some situations, diet, exercise, and behavior modification are not enough to lose weight.  In these instances, health care providers may prescribe a medication (diet pill) that will suppress appetite or decrease the amount of fat absorbed. These medications should be used in conjunction with lifestyle changes and not in place. Individuals trying to lose weight should only use diet pills approved by the FDA for weight loss. The FDA does not monitor over-the-counter weight loss supplements and does not recommend them for weight loss.

Bariatric surgery may be appropriate for individuals with a BMI over 40 or BMI over 35 with obesity-related coexisting conditions, so long as they’re motivated to lose weight and behavioral interventions (with or without medication) have not been effective. Potential candidates for surgery should be referred to an experienced bariatric surgeon for consultation and evaluation. ^[15]

Non-Diet Approaches to Weight Loss

In addition to weight management focusing on diet, exercise, and behavioral interventions, a growing movement centers around non-diet approaches. The trend is to have a healthier mentality toward food, weight, and body image. These approaches include establishing more beneficial relationships with food and more body acceptance and positivity, regardless of shape and size. Many of these programs center around our relationship with food and making eating an enjoyable experience. The focus is on well-being rather than dieting. They do away with shame or guilt, which are often associated with failed weight-loss efforts. They promote respect and inclusivity for all people, regardless of weight or size. Mindful or intuitive eating is a standard component of these approaches. ^[16]

To learn more about non-dieting approaches for a healthy lifestyle, check out the following video.

attributions

This section is an adaptation of “Best Practices for Weight Management” in Nutrition: Science and Everyday Application, v. 1.0 by Alice Callahan, PhD; Heather Leonard, MEd, RDN; and Tamberly Powell, MS, RDN licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.