This study won’t please anyone—not the low-carb fans, not the low-fat crowd, and certainly not the folks selling simple solutions.
Everyone wants to know which diet is best for losing weight. Low-carb or low-fat? Keto or Mediterranean? Intermittent fasting or six small meals?
But here’s the question almost nobody asks: Once you’ve lost the weight, what keeps it off long-term?
That’s what makes this study worth your time. Researchers followed 891 people who’d already lost at least 30 pounds and kept it off for at least a year. They tracked them for three more years to see what separated temporary success from lasting change.
When they compared the small group who used low-carb diets (96 people) against everyone else (795 people), what they found doesn’t fit neatly into any dietary tribe’s talking points.
The low-carb people ate more calories. They exercised less. They ate way more fat. And they had basically the same results as people doing the complete opposite.
If that makes you uncomfortable, good. The truth about keeping weight off is messier than any diet book wants to admit.
Key Takeaway: Different Diets, Same Success
Here’s what this study tells us: Different approaches work for keeping weight off long-term—but all require commitment.
The low-carb people kept their weight off eating nearly 500 extra calories per day. They exercised significantly less. Their diet was 64% fat—more than double what the other group ate.
Over three years, both groups gained back roughly the same amount: about 12-15 pounds on average.
That’s not failure, by the way. When you’ve lost 30+ pounds and you’re only up 12-15 pounds three years later, you’re winning. Most people gain it all back within a year.
The specific diet mattered less than finding something you could stick with. Think of it like different routes to the same destination—the low-carb folks found what worked for them and stuck with it. So did the low-fat crowd.
What this 3-Year Weight Maintenance Study Found
The National Weight Control Registry is a database of people who’ve successfully kept weight off. To get in, you need to have lost at least 30 pounds and kept it off for at least a year. Researchers enrolled 891 of these successful people and followed them for three years.
Only 96 people—about 11%—had used low-carb to lose weight. That’s your first data point. Low-carb works, but most people in the registry used other approaches.
When researchers compared these two groups at the start, the differences were big.
The low-carb group ate 1,895 calories daily. Everyone else ate 1,398 calories. That’s 500 calories more—roughly a full meal.
The low-carb people burned about 1,595 calories weekly through exercise, while others burned 2,542. That’s nearly 1,000 calories less—like skipping three or four workouts each week.
The fat intake difference was even more dramatic. The low-carb group got 64% of calories from fat. The other group got 31%. These aren’t small tweaks. These are opposite strategies.
The low-carb folks also ate more than double the saturated fat—23.8% versus 10.5%.
Researchers measured how much mental effort people put into controlling their eating. The low-carb group scored lower—10.8 versus 14.9. They felt like they were trying less hard to control what they ate.
After three years, both groups gained weight back. The low-carb group gained about 15 pounds. The other group gained about 12-13 pounds.
That difference means nothing statistically. Same outcome, different paths.
How to Apply This Study to Your Own Weight Maintenance
If you’re trying to lose weight or keep it off, this study offers something both freeing and challenging.
The freeing part: You have real options. Not just theory from diet books, but approaches that real people have used successfully for years.
Some people keep weight off eating 1,400 calories daily with 30% from fat. Others keep it off eating 1,900 calories with 64% from fat. Both work.
That 500-calorie difference matters when choosing your approach. If you’re always hungry on low-fat diets, you might be able to eat more by shifting to lower-carb, higher-fat eating.
If you don’t feel good without carbs and can manage on fewer calories, the lower-fat path might be yours.
The challenging part: Neither approach made keeping weight off easy. Both groups gained some weight back. Not all of it—they were still much lighter—but some came back.
This is the reality nobody talks about. You don’t just lose the weight and finish. You lose it, then enter a new phase that needs continued attention. Forever.
The people who did best found an approach they could sustain—not for six months or a year, but for years and years.
Stop looking for the “best” diet. Start looking for the diet you can live with. Can you imagine eating this way in five years? In ten? If not, it doesn’t matter how well it works short-term.
The Biology of Keeping Weight Off
Think of your metabolism like a thermostat that adjusts based on what you do to it.
When you cut calories hard, your body gets efficient. It learns to run on less. When you eat more fat and fewer carbs, your body shifts fuel sources and becomes better at burning fat.
The low-carb people eating more calories likely have higher metabolic rates because fat—especially with protein—takes more energy to process than carbs. Your body works harder to digest a high-fat meal.
But here’s what matters most: feeling full. Fat fills you up. So does protein. When your diet is 64% fat and likely high in protein, you feel satisfied without constantly thinking about food.
Remember that effort score? The low-carb group felt like they were trying less hard. That’s not willpower—that’s biology.
Their food choices made them feel full naturally, while the lower-fat group might have needed more conscious control and more careful decisions about portions.
That said, energy balance still dominates over months and years. Calorie density can sneak up on you on high-fat menus—fat is energy-dense, and portions still count.
The diet that fits your life and lets you maintain energy balance wins.
The exercise difference tells a similar story. The low-carb group exercised less but was still active—three or four moderate workouts weekly. The higher-exercise group did five or six workouts.
More activity provides a buffer against small slips, but you don’t need to live at the gym to keep weight off. Regular moderate activity is enough.
Debunking Low-Carb and Low-Fat Weight Loss Myths
Myth 1: “Calories don’t matter on low-carb”
The low-carb group wasn’t eating unlimited calories. Nearly 1,900 daily is still controlled for most people. The study doesn’t prove calories don’t matter.
It proves some people can keep weight off at higher calorie levels when those calories come from fat and protein.
That’s metabolic adaptation, not magic.
Myth 2: “You need intense exercise to keep weight off”
The low-carb people burned about 1,000 fewer calories weekly through exercise, yet they kept similar weight off. Exercise helps—both groups were active—but you don’t need to be extreme.
Myth 3: “High-fat diets will ruin your health”
I won’t tell you eating 64% fat is safe for everyone. This study didn’t measure detailed health outcomes beyond weight.
But these people kept significant weight off for years on very high-fat diets. The human body adapts more than our dietary rules suggest.
That said, the study authors noted that long-term health effects of keeping weight off with high-fat diets need more research. If your diet is high in fat, favor unsaturated fats where possible and ask your doctor for a lipid panel.
Myth 4: “There’s one best diet”
One group: 1,400 calories, 31% fat, lots of exercise. Other group: 1,900 calories, 64% fat, moderate exercise. Same three-year outcome. The “best” diet is the one you can stick with. Period.
Myth 5: “Once you lose weight, keeping it off is easy”
Both groups gained weight back over three years. This isn’t failure—it’s reality. Keeping weight off isn’t a finish line. It’s an ongoing process that needs planning and attention.
Real-Life Habits That Support Weight Maintenance
Here’s how to use these findings starting today.
1. Be honest about what you eat. Look at what you actually eat and could stick with long-term. Do you like higher-fat foods and feel good eating fewer carbs? Or do you feel terrible without pasta, bread, and fruit?
2. Try it for two weeks. Eat according to your preference and track how you feel. Curious about low-carb? Aim for 50-100 grams of carbs daily with higher fat, and notice your hunger, energy, and satisfaction. Like more carbs? Keep them moderate, lower the fat, then check in with yourself.
3. Stop comparing yourself to others. Your coworker lost 40 pounds on keto. Your sister kept weight off eating plant-based. What works in your body with your preferences is what matters.
4. Find exercise you’ll actually do—not what burns the most calories or what’s popular, but what you’ll actually keep doing for years. For most people, that’s 3-4 moderate sessions weekly. That’s enough.
5. Expect some weight to come back. Both groups gained some weight back, so build in flexibility from the start. Have a 5-pound window where you’ll adjust if needed, rather than expecting to stay at the exact same weight forever.
6. Weigh yourself weekly—not daily (changes too much day to day) and not monthly (too long to catch trends). Once weekly, same day, same time. Write it down. If you see it going up consistently over 3-4 weeks, adjust before it becomes 20 pounds.
7. Think of yourself differently. You’re not “on a diet.” You’re someone who keeps a healthy weight using your preferred approach. That shift—from temporary dieter to permanent keeper—matters more than you think.
8. Make it social-life friendly. If your plan isolates you or creates anxiety at every restaurant or family gathering, it won’t last. Build something that survives the messy parts of life.
9. Mind food quality. A high-fat diet from whole foods—nuts, olive oil, avocados, fatty fish—differs from one heavy in processed saturated fats. Quality matters for long-term health even if weight stays stable.
Weekly Weight Maintenance To-Do List
Pick one item and commit for three weeks:
- Track food photos for 7 days—no judgment, just data
- Do two 20- to 30-minute strength sessions
- Walk 20 minutes after dinner, 4 times this week
- Plan three healthy dinners for next week
- Weigh once each week, same time and clothes
- One item. Repeat. That’s how small wins add up.
Why This Research Matches Real-World Results
I’ve watched hundreds of patients try to lose weight. The ones who succeed long-term aren’t the ones who find the “perfect” diet. They’re the ones who find a good-enough diet they can live with forever.
This study makes me think about two patients in particular. One lost 35 pounds eating low-carb. She loves it, feels great, never gets hungry.
Bacon and eggs for breakfast, salads with chicken and full-fat dressing for lunch, salmon with butter and vegetables for dinner. She’s been keeping it off for six years now.
Another patient lost 40 pounds eating mostly plant-based, lower-fat meals. She feels terrible without rice or quinoa. She loves fruit.
The idea of eating 64% fat makes her feel sick. She’s been keeping it off for four years.
Both patients kept significant weight off. Each gained about 10-15 pounds after the first year, then stayed steady. Both exercise moderately—nothing extreme.
The difference between them and patients who gain it all back?
They found something they could stick with and accepted that keeping weight off takes ongoing attention. They didn’t jump between approaches looking for something easier.
The winners aren’t the ideologues. They’re the people who design routines that survive the messy parts of life. Pick something durable. If your plan causes social friction, anxiety, or bad labs, change it.
This study backs up what I’ve seen in practice: there’s no single path, but all successful paths need commitment to patterns you can live with.
The 500-calorie difference between groups shows bodies adapt differently. What matters is finding your way.
Where the Data Falls Short
This study has real limitations you should know about.
These people already succeeded. They’d already lost weight and kept it off for at least a year before the study began.
They’re not like everyone trying to lose weight. They’re the winners—the roughly 5-20% who manage to keep it off at all.
The low-carb group was small. Only 96 people out of 891. Small groups can show results that don’t hold up in bigger populations, so we need more data.
People chose their diets—this wasn’t randomized. That introduces selection bias.
We don’t know about their health beyond weight. The study tracked weight, diet, and exercise—not heart health or metabolic markers.
Eating 64% fat might keep your weight down, but what’s it doing to your cholesterol and arteries? We don’t know from this study, but that matters.
People are not accurate reporters about what they eat. They underestimate portions, forget things, and tell researchers what they think they should eat rather than what they actually eat. In this study, diet and activity were self-reported.
Three years isn’t that long. We really need 5-10 year data to understand true staying power.
Despite these problems, this study shows valuable real-world insight into how people actually keep weight off over time.
Applying the Research: Your Weight Maintenance Plan
If you’re actively trying to lose weight or keep it off, focus on this:
1. Pick based on what you like, not what’s popular. Low-carb, low-fat, moderate—they all can work. Pick what feels doable for you personally.
2. Give it time. The first few weeks of any new eating pattern are the hardest. Stick with it for 6-8 weeks before deciding it doesn’t work.
3. Move regularly. Aim for 3-5 moderate activity sessions weekly. Being consistent beats being intense.
4. Trend your weight weekly, don’t check it obsessively. Daily check-ins with weekly trending give you data without making you crazy.
5. Accept that keeping weight off takes continued work. You’re not broken if it takes effort. That’s how human weight regulation works.
6. Build habits instead of relying on motivation. Motivation fades. Habits stick around.
7. Remember: No macro will save you. Habits will. Pick one checklist item and commit for three weeks. If worried about heart health, favor unsaturated fats and get labs checked.
The people in this study weren’t superhuman. They were regular people who found what they could stick with and kept doing it. You can do that too.
Believe It: You Can Maintain Weight Successfully
Keeping weight off long-term is possible. It’s not easy, but it is certainly possible.
The data shows it. The people in this registry prove it. They’re regular people who found eating patterns and activity levels they could keep up for years.
Some eat low-carb. Other don’t. Some exercise a lot. Some only moderately. But they all kept significant weight off.
This means there’s a path for you. Maybe not your friend’s path or what you see on social media, but a path that works for your body, your preferences, your life.
Stop looking for perfect. Start building something you can stick with.
You did the hard part: you lost weight. Now your job is less about extremes and more about routine.
Build a few reliable habits, check simple metrics, and adapt when life changes. That approach beats ideology every time.
You’re not looking for the diet that makes you lose weight fastest. You’re looking for the eating pattern you can keep up when life gets hard, when you’re traveling, when you’re busy, when you’re celebrating, when you’re sad.
Find that, and you’ve found something better than any quick-fix diet.
Evidence-Based Help for Long-Term Weight Loss
If this made sense to you—the honest look at what works without the hype—my weekly newsletter breaks down exactly this kind of research.
I translate major weight loss studies into clear, useful information. I tell you what the science actually says about keeping weight off, explained the same way I’d explain it to a patient sitting in my office.
Join readers who want the truth about sustainable weight loss. You’ll get practical strategies backed by real research, the kind of insights that don’t fit neatly into anyone’s marketing story, and the honest reality about what keeping weight off actually takes.
