@DeficitLab

Deconstructing the biological mechanics of fat loss, fasting, and metabolic health. Data-driven protocols for busy people. Zero fluff.

 The Lab
Joined August 2026
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7 useful benchmarks for an above-average health profile: - Waist-to-height ratio: 0.40–0.49 - HbA1c: <5.5% - Fasting glucose: 75–95 mg/dL - Triglycerides: <100 mg/dL - hsCRP: <1 mg/L - Cardiorespiratory fitness: top 20% for your age and sex - Grip strength: top 20% for your age and sex Want to know what your health %-ile is? Take the quick assessment to get your score and find your biggest bottlenecks. Then start your program: skool.com/top1health Graphs: Grip strength (PMID: 39647778); VO2 (PMID: 34809986)
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Waist-to-height under 0.5 is such a handy one. A steady calorie deficit is the lever that actually moves it, and the tape measure tells you more than the scale.
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One of the funniest tricks in the American food industry is reduced-fat peanut butter. Regular PB must contain at least 90% peanuts (under FDA rules). But Jif's reduced-fat version is actually a "peanut butter spread" containing just 60% peanuts. Why? Because peanuts naturally contain fat. To reduce the fat, manufacturers remove some of the peanuts and replace them with ingredients such as corn syrup solids and pea protein. So you're buying something that's marketed as a healthier alternative that actually contains fewer peanuts and more added carbs. And the most hilarious part is that the FDA doesn't even allow them to call it peanut butter. They have to call it "peanut butter spread." Stories from the American food industry never cease to amaze me.
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Calories end up about the same as regular, so the "lighter" label saves you nothing. In a deficit I would just measure a normal serving of the real stuff.
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Exercising more to burn off what a person eats doesn't work the way most people think. As people get more active, their total daily calorie burn rises at first and then levels off. The body appears to adapt by spending less energy elsewhere, so the extra workouts don't add up the way the treadmill display suggests. Exercise is worth doing for muscle and fitness. For fat loss, diet comes first.
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This is why the deficit usually has to come from the food side. Extra workouts are great for health, but they rarely add up one for one on the scale.
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Here's what most guys don't understand about maintenance: The goal during maintenance isn't to eat as little as possible without gaining weight. It's the opposite. Eat as much as possible without gaining weight. Your body hates being in a deficit and the longer you stay there, the harder it fights back. Your metabolism slows, hormones tank, and your energy drops. So when you're done cutting, don't just hover in some weird middle ground. Start getting those calories back up and give your body the break it needs and deserves. Get your energy and training quality back. Then when you want to cut again, you'll have way more room to work with.
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Solid point. A proper break at maintenance makes the next deficit easier to run, since you can cut calories from a higher starting point.
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Lot of talk about “binge eating” right now post bodybuilding show. I’m currently right in this dilemma after stepping off stage on Sunday. I’ve had no binges at all but hunger signalling is 100% higher than ever. I’ve had a few good “off plan” meals that were already scheduled with the family. Enjoying within reason and not taking the piss with things. Training and steps are still in place etc. But all my other meals throughout the day have just been the boring staples. Oatmeal, rice, rice cakes, chicken breast etc.
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That hunger spike after a long deficit is normal, your body is pushing back hard. Boring staples plus keeping steps in is honestly the best way to stop the reverse turning into a rebound.
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Higher body fat is a better predictor of testosterone than age. Chronological age alone explained just 2.5% of the variation in total testosterone in men aged 20 to 59. Including measures of body fat, visceral fat, or waist circumference increased that to roughly 18-20%. And a simple waist measurement performed about as well as DXA-derived visceral fat for explaining differences in testosterone levels. A tape measure (something you can use at home) captured much of the same information as advanced imaging! This is one reason I talk so much about visceral fat (the fat surrounding your organs). Excess visceral fat can promote inflammation and insulin resistance, both of which can interfere with testosterone regulation. Fat tissue also contains aromatase, an enzyme that converts testosterone into estradiol, a form of estrogen. The relationship can run both ways - lower testosterone can favor fat accumulation, creating a feedback loop. These are observational data, but they suggest some of what gets labeled “age-related” low testosterone may be more closely tied to body composition.
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Good news is your waist is something you can actually move. A steady calorie deficit shrinks it, and the tape measure tracks it better than the scale some weeks.
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The fat burning zone is a percentage trick: Sleeping is the highest percentage of fuel coming from fat of any activity you could ever do. If staying at low intensity burned more fat, the optimal strategy would be to sleep. At lower intensity a greater percentage of your fuel comes from fat, but total fuel expenditure is very low, so total carbon balance barely shifts. Same reason fasted training is irrelevant. With muscle glycogen, liver glycogen and blood glucose at sufficient levels, you have plenty of fuel sitting around. @DrAndyGalpin on @hubermanlab
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Fat loss comes down to total energy balance over days and weeks, not which fuel you burned during the session. Zone 2 is great for health, but the deficit is what drives the fat loss.
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Most restrictive diets work great. For about nine months. Studies show people can stick to cutting out bread, pasta, rice, whatever, for 3 to 9 months. By the one year mark, most are back to eating the way they always did. So I stopped telling patients to quit foods they have eaten for 30 to 40 years. I tell them to eat the same stuff. Just less of it. The diet was never the problem. The deadline was.
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Eating the same stuff, just less of it, is still a calorie deficit. It's just one people can actually keep doing.
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If you put processed foods in your pantry and freezer, you have to have the same battle 10 times per day. That's more than 3,600 chances to lose an argument with your own refrigerator. I don't care how strong your willpower is, if you buy the Oreos, you will eventually eat the Oreos. Fix what's in reach. Make the hard decision in the grocery store, and every battle becomes easy.
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This is underrated. Most deficits don't fail at dinner, they fail at the 9pm pantry visit, so making the call at the store does half the work for you.
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I’m 44 years old, have an 11-month-old baby, and I’m stronger than I’ve ever been. I’m also leaner than I’ve been since I was a teenager. And no, I didn’t win the genetic lottery. I was overweight, hypertensive, and prediabetic in my late 20s. I also suffered from chronic back pain. My family history puts me at high risk for hypertension and type 2 diabetes. I turned my health around by changing how I eat. But here’s what I’m most proud of. Most of my strength gains happened in the last 6 months, after I committed to resistance training at least 4 times a week. In my 20s, I could barely do 3 pull-ups Today, I can do 14 slow, controlled pull-ups with full range of motion. And I’m doing this while raising an infant, with interrupted sleep and plenty of reasons to skip workouts. I don’t take any medication or supplements except vitamin D. I’m not sharing this to impress you. I’m sharing it to remind you what’s possible. You don’t need perfect circumstances. You don’t need to wait until life slows down. You don’t need to feel motivated every day. You need to make a decision, commit to it, and keep showing up. Eat real food. Prioritize protein. Lift weights. Stay consistent. Stop putting junk in your body. Your genetics aren’t your destiny. Your age isn’t an excuse. And your past doesn’t have to dictate your future. Imagine where you could be 6 months from now if you started today.
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Love that the strength came after the eating changes. Real food and high protein make it so much easier to stay in a deficit without white-knuckling it.
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YOU DON'T NEED A SLOW REVERSE • There's little evidence that slow reverse diets beat a direct jump • Going straight to maintenance is usually fine • Expect a quick 1 to 3 pound bump on the scale • That's food, water, and glycogen, not fat • Watch the 2 to 3 week trend, then adjust The cut is over. Eat at maintenance and hold it.
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How to build a top 1% metabolism after 45: 1. Walk 8,000+ steps every day 2. Sleep 7+ hours in a cold, dark room 3. Eat 30g+ of protein within 1 hour of waking 4. Cut alcohol, or cap it at 1–2 drinks per week 5. Strength train 3x/week (and actually lift heavy) 6. Finish your last meal at least 3 hours before bed 7. Avoid ultra-processed foods, seed oils, and mindless snacks Do this consistently, and your body becomes very good at burning fat and staying lean.
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Solid list. Worth adding that none of these burn fat on their own, they just make it way easier to stay in a calorie deficit.
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Doing cardio in the morning is a cheat code for energy. Combined with coffee you’re literally unstoppable.
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Morning cardio for energy, 100%. For fat loss the timing barely matters though, it's the weekly calorie deficit doing the work.
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Bryan Johnson
@bryan_johnsonOct 19
Two poor nights of sleep and I instantly feel my otherwise perfect will power become dimished.
Bryan Johnson
@bryan_johnsonOct 17
I got 4 hr 41 min of sleep 😭
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Short sleep tends to push up hunger and cravings the next day, which is why a deficit feels so much harder after a bad night.
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Cardio is overrated for fat loss And severely underrated for mood
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Agreed, you can't outrun your diet. The deficit does the fat loss, cardio just makes the whole process feel better.
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Zero-calorie beverages beat full sugar beverages every time when you're losing weight. If you prefer water, drink water. But don't be so scared of artificial sweeteners.
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Swapping one regular soda a day for diet saves roughly 140 calories, which adds up fast in a deficit. Easiest win most people overlook.
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Unfortunately, the whole ‘lift 3x a week, 10k steps a day, eat a real food diet, get sunlight, sleep 7-9 hours, stay hydrated, and be consistent’ thing actually works. The fitness industry just doesn’t want you to believe it’s that simple.
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Underrated part is how much that boring list helps with fat loss. More steps, better sleep and real food all make a calorie deficit way easier to stick to.
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Eat your lunch outside today without your phone. Distracted eating suppresses satiety hormones, increases how much you eat, and reduces nutrient absorption from the same meal. Eating outside without a screen: - Satiety signals work as designed - Midday light supports serotonin production - Genuine mental rest improves afternoon focus - Parasympathetic activation improves digestion Same food. Twenty minutes of difference. Completely different afternoon.
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Distracted eating tends to mean you eat more without noticing. Eating without a screen makes a calorie deficit a lot easier to hold.
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Not sure who needs to hear this but if your “meal” isn’t high in protein, it’s not a meal, it’s a snack.
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Protein is the cheat code in a deficit too. It keeps you full on fewer calories, so sticking to the deficit feels way less like a fight.
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Everyone wants the 90-day transformation. Nobody wants the 12-year consistency. I've been in the gym for 12 years without ever "taking a break" or falling off. That's it. That's the whole strategy. You just need to stop quitting.
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This is the part nobody puts in the before and after. A modest deficit you can actually stick to beats an aggressive one you quit in week 3.
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