How To Stop Overeating: What I Learned Swapping Diets With A Couple 3x My Size

How To Stop Overeating: TL;DR

For 24 hours, I ate the exact diet that got a man to over 50% body fat while he and his wife ate the diet that keeps me at 10%. His day came to 8,312 calories; theirs came to 1,994. But the biggest differences weren’t on the plate — they showed up in our brain scans, and in seven science-backed habits that made the healthy version of the day so filling that neither of them could finish it. If you’ve ever wondered how to stop overeating, the real answer had less to do with willpower than with these specific habits. Here’s what happened, and the strategies you can copy.

Key Takeaways

• The calorie gap was enormous, but the food wasn't that different. Cam's usual diet totaled 8,312 calories (422g fat, ~1,000g carbs); the healthier version of the same day came to 1,994, and left them too full to finish.
• Overeating is driven by brain wiring, not just discipline. EEG scans showed Cam's reward center lit up at fast food, while a stronger self-control response made resisting easier, and both can be trained.
• Seven habits do the heavy lifting. Add crunchy/chewy foods, swap full-sugar soda for diet soda, control your food environment, train self-control by doing hard things, eat without screens, practice saying no, and use smaller utensils.
• Ozempic quiets cravings but doesn't erase them. Michelle's "food noise" was gone — until she tasted dessert, at which point her reward response spiked even higher than Cam's.
• Volume and protein beat hunger. Higher-volume, higher-protein meals let them eat far fewer calories without feeling deprived.
• Small, repeatable changes win. Cam dropped 3 pounds in a single day and agreed to a year-long transformation; no extreme diet required.

The 24-Hour Diet Swap: How It Worked

What happens if you swap diets with someone who weighs three times your size? That was the experiment. For one full day, I ate the exact daily diet that got Cam to over 50% body fat, while Cam and his wife Michelle ate the diet that got me to 10% body fat.

But this was more than a diet swap. One week earlier, I brought all three of us in for EEG brain scans to investigate a bigger question: how to stop overeating — more specifically, why some people can’t stop eating, and whether lasting change is really possible for anyone.

As one of the experts put it after reviewing our results: “The response we see in each of your brain scans couldn’t be more different.”

We started with a morning weigh-in, planning to weigh in again the next day to see how a single day of eating had moved the scale. Then it was time to eat.

What The Brain Scans Revealed About Overeating

A week before the swap, the doctors ran our scans in two phases. In the first phase, each of us simply stared at a plate of McDonald’s burgers and fries for five minutes.

How Cam’s Brain Reacted To Food

The brain’s reward center is the region that decides how irresistible food feels. If you’ve ever seen a bag of chips or a box of donuts and felt like it was calling your name, that’s the reward center driving the craving. In Cam’s scan, a dark red area lit up at the front of his brain — his reward center was absolutely on fire.

Cam described himself as a creature of habit: “I’m very much habit oriented… for me to try and change really anything, the smallest things kind of just cause me distress.”

How My Brain Reacted Differently

My scan looked nothing like Cam’s.

My reward center barely reacted. Instead, most of the activity shifted to the brain’s self-control center — the system that helps you pause and think twice when something doesn’t line up with your goals. Before either of us had taken a single bite, our brains were already playing by completely different rules.

Why Michelle’s Brain Barely Responded

Then we looked at Michelle’s scan, and it was as if she wasn’t looking at food at all.

Instead of activating her reward system, her brain mostly processed the burgers and fries as ordinary visual objects. As the expert described it: “What we see in Michelle’s results is someone responding to food the same way you’d expect if you just asked them to look at a pair of candlesticks — two neutral objects with little emotional significance.”

Michelle’s brain isn’t “broken.”

She’d been taking Ozempic, a prescription medication designed to reduce the appeal of food — for the past year. It hadn’t completely solved her eating struggles (more on that in phase two), but she’d been taking real steps toward a healthier lifestyle and had agreed to work with me on a year-long transformation.

There was a catch: Michelle could only succeed long-term if Cam, who’d been resistant to change, agreed to join her. So, at the end of the day, we’d ask Cam for a yes-or-no.

The Dessert Test: When Cravings Overpower Ozempic

The good news is that Cam’s brain isn’t stuck. Reward can be dialed down, and self-control strengthened, and the healthy diet is built around seven science-backed ways to do exactly that.

But first, phase two of the scan revealed something none of us expected.

All three of us ate a simple lunch until we were full. Then we were handed a plate of desserts and told to eat as much as we wanted. As the expert explained: “When we monitor Michelle’s brain after having dessert, all of a sudden that reward center that wasn’t responding earlier is now lighting up. In fact, at this point it’s even higher than Cam’s.” In other words, once Michelle tastes some of her favorite food, her reward response is strong enough to overpower Ozempic's effect.

Cam recognized the feeling: “If I’m into the dessert already, I’m like, oh, I’ve already crossed the line, so I might as well go all in.”

How To Stop Overeating: Seven Science-Backed Strategies

The short version of how to stop overeating is this: you don’t rely on willpower; you change the conditions that trigger it.

Across the day, I built seven science-backed habits into every meal, each one designed to dial reward down, build self-control up, or make food naturally more filling. Here’s how each one played out, starting with the very first meal.

Breakfast: 1,674 Calories Vs 474 Calories

Cam’s go-to weekend breakfast was a sausage McGriddle, a sausage egg McMuffin, two hash browns and a large Coke, what he calls “the hangover cure in a paper bag.” He also had a real thing for a fizzy drink with food, something I admitted I understood.

For Cam and Michelle, I made a high-protein French toast: three slices of whole-grain bread soaked in one whole egg plus egg whites and a little sweetener, then pan-fried, served with caramelized sautéed apples and cinnamon, two slices of turkey bacon, and sugar-free syrup. It’s a lot of food for surprisingly few calories — the kind of meal I’d eat while dieting.

Strategy 1: Add Crunch To Slow Down Your Eating

One thing fast-food chains are very good at is texture: the food is usually soft, which makes it easy to overeat.

So I try to build a more solid, chewy component into my meals. The chew slows your eating down and helps you get more satisfaction (more “pull”) from the meal, which is the real reason those caramelized apples are in the French toast. It’s the same principle behind building high-volume, filling weight-loss meals: more food and more chew for fewer calories.

That one change might be why I’d already finished breakfast while Cam and Michelle were still going — and why they were surprised to feel genuinely full.

Cam still swears by his usual McGriddle — “top tier,” he calls it — but the tell was that his normal breakfast tends to leave him still hungry and reaching for the rest of his Coke, the opposite of how stuffed the French toast had left them (“Literally too much,” as he put it).

When we tallied the calories in my app, Cam’s McDonald’s breakfast came to 1,674 calories. The French toast plate, everything included, came to 474.

“This is double. This was double, triple,” Cam said. Even going in skeptical, he came out convinced: a healthy breakfast like that could be both delicious and calorie-smart.

Lunch: 1,545 Calories Vs 408 Calories

Cam’s everyday work lunch was a grab-off-the-shelf assortment: a bagel with cream cheese, a cookie, two granola bars, a banana, a full-sugar Coke, and two string cheeses — plus another Coke.

His theory was simple: on the road, a hot lunch is tough, so he snacks throughout the day. Vegetables rarely featured; a piece of fruit was usually the only produce.

For lunch, I made barbecue chicken fajitas: pre-made grilled chicken, prepped vegetables, fresh lettuce, wraps on the side, and a sauce of sugar-free barbecue sauce cut with mayo, plus a diet soda.

By this point in the day, I’d already had over 100 grams of sugar from Coke alone, and I was feeling it.

Cam, meanwhile, told me he drinks around four Cokes a day, with Michelle adding, “and one in the middle of the night.” Cam described getting up between midnight and 3 a.m. to slam half a cold Coke, then finishing the rest on his way to work. Which leads straight into the second strategy.

Strategy 2: Swap Full-Sugar Soda For Diet Soda

When people switch from full-sugar Coke to diet soda, they tend to lose weight.

In one year-long randomized trial, researchers took people who regularly drank diet soda and had one group stop and switch to water instead, while the other group kept drinking diet soda. The group that kept the diet soda actually lost more weight over the next year and kept it off. The idea is that a fizzy, sweet drink after a meal helps eliminate the craving — otherwise you’re left searching for something sweet. It’s one of several simple food swaps that make fat loss easier.

The calorie gap held: Cam’s typical lunch came to 1,545 calories; the fajita lunch came to 408.

As Cam put it, the bagel is “sneaky”; it doesn’t look like much, but the cookie, granola bars and Coke (around 140 calories each) all add up. By the time I finished lunch I was already well over 3,000 calories — enough, for me, to gain almost a pound a week on just those two meals. (If you’re curious what your own numbers look like, you can estimate your daily burn with the Built With Science TDEE calculator.)

The fajitas weren’t a runaway hit, to be fair.

Cam rated them a 6.7 — the vegetables were a bit much for him, and the sugar-free barbecue sauce didn’t quite land. With three swaps still to go, I was hoping to raise my average.

Strategy 3: Change Your Food Environment

The single most important strategy for Cam and Michelle might be the simplest: control what’s in the house. Michelle put it plainly — if a cheesecake is around and you have a bite, “that’s game over.” She remembered a day with donuts: Cam bought six because he wanted them, and she went home and ate three jelly donuts, something she’d never done in her life, just because they were there.

Even with a strong self-control center, Cam agreed he couldn’t fight that temptation 24/7. The fix is to keep the kitchen clear of chips, cheesecake and donuts because the real choice starts at the grocery store, and making those choices together is part of doing this as a couple.

Around this point, Cam opened up about his weight.

Ten years ago, he was about 130 pounds lighter; after losing his dad, he went to a dark place and stopped living a healthy lifestyle, and the weight kept coming. “You don’t really notice, and then all of a sudden your clothes don’t fit… and that’s just your new normal.” A year ago, he learned he was pre-diabetic and was put on medication, which scared him, especially with family in medical fields reminding him that ignoring it only makes it worse.

Michelle’s motivation had a face, too: her sister Nicole, a nurse, who, along with her husband, recently followed the nutrition and workout plan from our Built With Science app as a case study and completely transformed in just a few months.

That gave Michelle hope, especially since the weight-loss medication she’d taken for over a year hadn’t solved her struggles. As she described the effect of Ozempic: “I just feel like the food noise has gone away… I’m not always thinking, oh, I need a cookie, I need a bag of chips, I need to eat something all the time.” That matched phase one of the brain scan exactly — but as phase two showed, dessert could still flip that switch back on.

The Gym: Training Self-Control By Doing Hard Things

Next, I ran Cam and Michelle through a basic workout they could stick with twice a week, at the gym or at home — partly to prevent muscle loss as they lose weight (which also comes down to getting enough protein), and partly because of something Cam said at lunch.

When I asked him for a deep “why,” his answer worried me: “It’s 100% for Michelle. That’s the only reason I’m here.”

So I hoped the weights could give Cam a personal goal. It worked faster than expected. Carrying nearly 380 pounds turned out to be a hidden strength advantage: Cam is effectively moving that weight around all day, which translates into serious pressing power.

He lit up: pushups, then heavier lifts, and a memory of doing the whole stack in high school. “Just pushing weight again… it’s like lighting a fire. Growing up was very competitive, and I want to be that person again.” His dad’s words stuck with him: “It’s okay to be bigger. Just don’t let it slow you down.”

Strategy 4: Train Self-Control By Doing Hard Things

Here’s the part that ties the workout back to the brain.

That self-control center that helps you resist temptation isn’t only trained by choosing healthier food — it’s also trained by doing hard things. Grinding through a tough set of squats while you’re huffing and puffing trains the same “I’m going to do it anyway” response you use to turn down a craving. That’s why I made exercise a core part of their long-term plan.

And the pair were already feeling the difference.

They said that if they’d eaten McDonald’s, they wouldn’t have wanted to be in the gym at all. When I admitted I didn’t feel like working out after a day on their diet, Michelle laughed: “So how we feel every day!” They’d never even realized how lethargic their usual eating made them feel; “it’s been so long eating like that, we just feel normal. That’s our normal.”

Snacks: The Hidden Calories Of Everyday Eating

For snacks, Cam reached for another Coke, chips, and a PB&J — a bedtime staple if he’s still hungry — plus a protein bar. My version: as many baby carrots as I want with a bit of hummus, and one protein bar. (Modern protein bars, for the record, have gotten genuinely good; the couple was pleasantly surprised.)

Chips were the real theme. They’re always around the house, always accessible, and, Cam admitted, probably the problem.

And they’re rarely eaten with attention: doomscrolling on the phone, or on the couch with a game or a movie.

Strategy 5: Practice Mindful Eating

Mindful eating means paying attention to what you’re actually eating instead of eating while distracted.

The pull to keep eating while distracted is powerful. In one study, researchers gave moviegoers either fresh, tasty popcorn or popcorn that was a week old and noticeably stale. Both groups ate almost the same amount — even though the stale-popcorn group openly admitted they weren’t enjoying it.

Whenever you can, put the phone down for a bit and actually pay attention to your food. You’ll find it makes a noticeable difference in how satisfied you feel after the meal.

Strategy 6: Practice Saying No

Here’s what Cam and Michelle didn’t know: through every meal that day, I’d been quietly strengthening the self-control centers of their brains — by eating their favorite bag of chips in front of them while they stuck to protein bars and carrots.

Every time you resist a temptation like that, you’re telling your brain the reward system isn’t in complete control, and the more you do it, the stronger that self-control gets.

This isn’t about buying a bag of chips and staring at it at home.

It’s about the grocery store: every time you resist putting the chips in the cart, you make that muscle stronger, and that’s what helps long-term. Later, when I fought my own craving for a Coke, I felt exactly how hard that is — that day’s sugar total had climbed to 306 grams, over ten times the recommended daily limit.

Building this kind of resistance around foods you actually like is a big part of making a fat-loss diet stick.

Dinner: ~2,000 Calories Vs 572 Calories

Dinner was Cam’s fettuccine Alfredo with Cajun chicken and garlic toast: chicken breast pan-fried in oil, regular noodles in a jar of pre-made Alfredo sauce, and buttery, cheesy garlic bread — a typical portion.

My version looked similar but was built differently: a base of sautéed vegetables and ground beef with tomato sauce thickened with light cream cheese, over noodles that were half regular spaghetti and half nearly calorie-free spaghetti, finished with a little parmesan and salt. Cam noticed the swap; some noodles tasted regular, some almost like an Asian-style noodle, but agreed it was hard to tell with the half-and-half mix.

Using the meal scanner, Cam’s pasta came in around 2,000 calories (without the Coke); mine came to 572.

Strategy 7: Use Smaller Utensils

Your brain takes roughly 20–30 minutes after eating to register that you’re actually full.

So, just like adding crunchy, chewier foods, smaller utensils force you to slow down and give those fullness signals time to catch up. (Cam was not a fan of the small forks: “Why did you get me the salad fork? I feel like I’m a baby.”)

By dinner, I could feel the pull to the dark side myself — a Coke with dinner, and the strange sense of a craving that “keeps coming back.”

Cam and Michelle, meanwhile, had the opposite problem. “I kind of thought dieting would be me just being hungry all the time,” Cam said. “And I can’t even finish my dinner. That goes for all the meals — extremely filling and satisfying.” That reaction was the opening I’d hoped for: I set them up with our app, which is full of recipes like these, and sent them home with a copy of our cookbook.

Dessert: The Best Part Of A Healthy Diet

Dinner wasn’t quite the end.

In the freezer was dessert made with a Ninja Creami. For Michelle, a cheesecake version (sugar-free pudding, milk, one scoop of vanilla protein, light cream cheese); for Cam, a chocolate version (light chocolate milk, sugar-free chocolate pudding, half a scoop of protein, and a serving of powdered peanut butter).

For myself, I had a half-pint of Ben & Jerry’s with a Nesquik chocolate milk.

Michelle turned out to be my toughest critic — “I’d just rather not eat a sweet treat after dinner” — but Cam was sold: “I love it. I don’t know if it could be any better.” Setting him up with two desserts he loved gave me hope he’d say yes at the end of the day. To help them start, I gave them a Ninja Creami of their own.

The Results: 8,312 Calories Vs 1,994 Calories

When we tallied the full day, Cam’s diet came to 8,312 calories — 422 grams of fat and almost 1,000 grams of carbs. “It wasn’t actually that much food,” he said. “It just adds up.” The diet Cam and Michelle ate came to 1,994 calories, with 61 grams of fat — a clear deficit, especially since they often couldn’t finish the meals.

The deficit is even bigger than it sounds for Michelle.

When we tested her metabolism in a previous video, she was naturally burning over 3,000 calories a day just from carrying her body weight. Stick anywhere close to this diet, and she’d lose well over two pounds a week without changing anything else. Her verdict: “Very eye-opening. Very achievable.”

Then the final weigh-in. I was up two pounds — not as bad as I’d feared. Michelle’s weight stayed exactly the same, and Cam’s dropped three pounds. A one-day change can happen for lots of reasons, but I hoped that small nudge would be enough.

Michelle asked the question the whole day had been building toward: “Final decision time. Are you going to join me on this or not?” Cam paused long enough that it looked like a no — then: “100%. I’m in.”

How To Stop Overeating: The Bigger Takeaway

The plates told one story: 8,312 calories versus 1,994.

But the brain scans told the more important one, and it reframes how to stop overeating entirely. Reward and self-control aren’t fixed — reward can be dialed down and self-control built up, through the food you keep in the house, the meals you slow down to enjoy, the temptations you practice turning down, and the hard things you choose to do.

Cam and Michelle didn’t just eat fewer calories for a day; they got a preview of a way of eating that left them full, satisfied, and — for the first time in a long while — hopeful.

Want to find your own starting point? Use the Built With Science calorie calculator to get a target for fat loss, maintenance or muscle gain, then learn how to set a target you can actually stick to in our guide on how to calculate your calorie deficit.

How To Stop Overeating:Frequently Asked Questions

A big thank you to the doctors at Elumind, who conducted and interpreted our brain scans.