Injections, patches, meal replacements, fiber supplements, and appetite teas in cheerful packaging make the weight loss section of any pharmacy in America or Britain appear more crowded than ever. Globally, the diet industry makes more than $70 billion annually, but the long-term weight loss statistics are still, by all accounts, appalling. Within two years, over half of the weight lost in clinical trials is gained back. The percentage rises above 80% after five years. That figure was derived from a 2018 meta-analysis of 29 long-term weight loss studies, and it hasn’t significantly changed since. The products continue to grow. The biology remains unchanged.
Timothy Lohman and Laurie Milliken begin their 2025 book, The Science of Long-Term Weight Loss, published through Human Kinetics, at this uncomfortable beginning point of serious obesity research. Lohman, an emeritus professor at the University of Arizona who has spent more than fifteen years researching body composition and the obesity epidemic, approaches the issue in the same way that an engineer might approach a persistent structural failure: by challenging the model being employed rather than the individuals who fail. He contends that the majority of weight loss programs are intended to produce immediate results. The biology of maintenance is a completely different issue that calls for a different set of instruments.
| Reference book | The Science of Long-Term Weight Loss — Timothy G. Lohman, PhD & Laurie A. Milliken, PhD, FACSM (Human Kinetics, April 2025) |
| Lead author background | Prof. Lohman is professor emeritus at the University of Arizona and president of the Global Health and Body Composition Institute; 15+ years researching obesity and long-term weight loss |
| Co-author background | Dr. Milliken is associate professor, University of Massachusetts Boston; CEO, Global Health and Body Composition Institute; fellow of the American College of Sports Medicine (ACSM) |
| Key research finding | In a meta-analysis of 29 long-term weight loss studies, over half of lost weight was regained within 2 years; by 5 years, more than 80% was regained (Hall et al., 2018, PMC/NIH) |
| Metabolic adaptation | For every kilogram lost, daily energy expenditure decreases; appetite simultaneously rises above baseline — creating a strong biological drive toward weight regain |
| Recommended activity level | ~60 minutes or more of daily physical activity to maintain significant weight loss (NIH / ACSM guidance) |
| Sustainable loss rate | 1–2 pounds per week; rapid or extreme dieting associated with faster regain |
| Obesity epidemic onset | Began in the 1980s; continues to affect U.S. and global populations in the 21st century |
| Successful maintenance rate | Only ~20% of overweight individuals achieve long-term weight loss (defined as losing ≥10% body weight and keeping it off) — Wing & Phelan, 2005, ScienceDirect |
| Key topics covered | Food addiction, exercise resistance, night eating syndrome, emotional regulation, cognitive behavioral therapy, environmental factors, group support, continuous care |
| Multidisciplinary approach | Best outcomes involve dietitians, physicians, psychologists, and fitness professionals working together |
| Reference / source | NIH / PMC — Maintenance of lost weight and long-term management of obesity (Hall et al., 2018) |
Metabolic adaptation is the fundamental problem, which diet culture noticeably avoids talking about. The body doesn’t just accept the new situation when someone loses weight. It reduces energy expenditure and simultaneously increases appetite above baseline, registering the change as a sort of emergency. The effect is quantifiable: hunger hormones increase and daily calorie requirements decrease for each kilogram of weight lost. In a very real sense, the body is retaliating. Many people who regain weight after a successful diet may be struggling against a biological current that most short-term programs never prepare them for, rather than failing due to a lack of discipline. Both personally and clinically, that distinction is very important.
Johns Hopkins and National Institutes of Health research reveals what appears to be effective over time, and it’s not particularly dramatic. It is recurring. According to a widely cited 2005 study by Rena Wing, people who successfully maintain significant weight loss—roughly 20 percent of those who try—tend to share a cluster of behaviors: regular self-monitoring, eating breakfast, sticking to regular meal schedules, consistent daily activity (often around 60 minutes or more), and maintaining a reduced-fat diet.
These are all not revolutionary. Successful maintainers differ from the majority in that they continue to do these tasks for years rather than just a few weeks. In many respects, the maintenance phase is more difficult than the loss phase. The effort is no longer novel, there is no discernible progress to monitor, and compliments are not coming in at the same pace.
Lohman and Milliken’s strategy heavily relies on complexity science, which holds that obesity is an emergent outcome of interacting factors such as genetics, food environment, sleep, emotional regulation, social support, and policy rather than a single-cause issue that can be resolved with a single-cause intervention. This framing, which is still rather uncommon in popular weight loss discourse, moves the focus from personal willpower to the system that surrounds the individual.
A person with a nutritionist, a home gym, and flexible work hours faces a very different challenge than someone trying to maintain weight loss while working night shifts, living close to cheap fast food, managing chronic stress, and getting five hours of sleep. When those two scenarios are treated the same way, as is the case with most commercial diet programs, the outcomes are predictably different.
As the current wave of GLP-1 medications, such as semaglutide, sweeps through the field of obesity medicine, it seems as though science is finally catching up to the complexity that researchers have been describing for decades.
The long-term effects of these drugs are still unknown, but they do work in a significant and quantifiable way. After stopping the medication, many patients put on weight again. The food environment, metabolic set points, and underlying behaviors have not altered. Without necessarily treating the conditions that cause the symptoms, the medications suppress them. That’s not an excuse to write them off; rather, it’s a reason to consider what might come next.
It’s difficult to ignore how much of the recommendations found in thorough obesity research seem modest in comparison to what is found on the shelves and in the feeds of the wellness industry. Every day, spend sixty minutes moving. regular meals. frequent weigh-ins. a group of people around you, such as a doctor, dietitian, or even a psychologist.
These are unglamorous and genuinely hard to obtain for a lot of people. They don’t work well for advertising. However, the evidence that has been gathered over decades of meticulous investigation consistently points in the same direction. Long-term weight loss is more of a series of daily choices made within a biology that never completely stops pushing back than it is a destination.
