Why you're not losing weight

If you’re not losing weight, you’re almost always eating at maintenance without knowing it. The usual causes are bites and drinks you don’t log, weekends, a maintenance guess that’s too high, eating back workouts, and a deficit that shrank as you got lighter.

“I’m in a deficit and nothing is happening”

This is the most common complaint in weight loss, and it usually ends one of two ways. People decide their metabolism is broken, or that calories don’t work for their body. Both feel true, because they really are eating less than before and the scale really isn’t moving.

A real deficit works every time. What fails is a deficit that only exists on paper.

Think of it like paying down a credit card. Pay $500 off every weekday, spend $1,500 over the weekend, and the balance barely moves, even though five days out of seven you were doing great.

Mistake 1: you’re eating more than you think

In 1992 a team of researchers studied 10 people with obesity who said they couldn’t lose weight however little they ate. They measured what these people burned and what they ate over two weeks. Their metabolism was within 5% of what was expected for their size. On average they’d underreported their food by 47% and overreported their exercise by 51%.

Nobody in that study was lying on purpose. Most of the missing calories are the ones that don’t feel like food.

• Drinks. Coffee with milk and sugar, juice, smoothies, alcohol.
• Cooking fat. Oil and butter add up fast, and a pan takes more than you’d guess.
• Bites and tastes. The kids’ leftovers, a handful from the office bowl, tasting while you cook.
• Restaurant meals. You don’t see the butter.
• Labels. US rules let a food’s real calories run up to 20% over the label.

Log everything for two weeks, weekends included, and weigh the dense foods. Most people find the gap in the first few days.

Mistake 2: the weekend

Researchers in St. Louis followed 48 adults aged 50 to 60 for a year, one group cutting calories and one exercising daily. During the week, both groups lost weight. On weekends the calorie group stopped losing, and the exercise group gained.

Here’s how that adds up for someone who maintains on 2,500 calories a day.

You don’t have to stay home. Look at your weekly average instead of each day, keep logging on weekends, and if Saturday will be big, eat a protein-heavy breakfast and lunch so you don’t arrive starving.

Mistake 3: your maintenance guess is too high

Every calculator gives you an estimate. The best formula, Mifflin-St Jeor, comes within 10% for more people than any other, and that still leaves real errors for some. On a maintenance of 2,400 calories, 10% is 240 a day. If you planned a 500 calorie deficit and your real maintenance is 250 lower than the calculator said, half your deficit was never there.

Your scale tells you which way the calculator missed. If three or four weeks of trend are flat, your real maintenance is about what you’re eating now. Take 100 to 200 calories off that, and wait another three weeks.

Mistake 4: you didn’t adjust as you lost

A lighter body needs less food. NIH researchers worked out that each pound you lose lowers your maintenance by about 10 calories a day. Lose 20 pounds and the deficit you started with is about 200 calories smaller.

When researchers checked the 3,500 calorie rule against seven tightly measured diet studies, it predicted about 28 pounds lost. People lost about 20. Re-work your numbers every 10 to 15 pounds. Why your burn drops covers the rest of the slowdown.

Mistake 5: you’re eating back your workouts

Watches guess calories badly. In a Stanford test of seven wrist devices, the calorie estimates were off by 27% to 93%. And your body makes up for about 28% of what activity burns, on average, more in people with more bodyfat. If your watch says you burned 600 and you eat 600 more, you may have eaten back the whole workout and some of your deficit too.

Set your calories from your average week and leave the workout out of the math.

Mistake 6: you judged it too soon

The first week of a diet drops water, and the scale moves fast. Glycogen in your muscles and liver is stored with three to four times its weight in water, and it leaves when you eat less. Then the fast drop stops, the weight sits still for a week or two while water shifts, and people decide the diet stopped working.

Fat comes off slower than water. Judge three or four weeks of trend, not the second week.

Mistake 7: all or nothing

It usually looks like this. A strict plan for three weeks, one pizza night, and then “the diet’s ruined, I’ll start again on Monday”. The pizza was a few hundred calories over. The week of giving up afterward was the real damage.

In a 2010 study at University College London, 96 volunteers each picked a new eating, drinking or exercise habit to do every day, and tracked it for 12 weeks. The time it took for the habit to feel automatic ranged from 18 days to a projected 254. Missing one day didn’t change the curve.

• Plan for 80 percent. Most of your meals follow the plan, and some don’t. That’s the plan working.
• Never miss twice. One off day is noise. Two in a row is the start of a new habit.
• Don’t ban the food you love. Have the pizza with a salad first, or on Saturdays only.
• Only do what you could do every day for a year. A 5 am run you quit after a week loses to a walk you keep.

Mistake 8: starting with the gym instead of the kitchen

New plans often start with daily workouts and the same food. You can eat in a few minutes what takes an hour to burn, and your body makes up part of what you burn. Exercise is important for your muscle and your heart, and it’s a poor way to make a deficit. Lifting, walking and cardio has the full case. Fix the food first, then add the training.

Mistake 9: the food fights you

A deficit made of the same packaged food, just less of it, leaves you hungry. In an NIH ward study, 20 adults offered ultra-processed food ate about 500 calories a day more than on unprocessed food, without trying to. If your plan only works when you’re starving, you’ll eat your way out of it eventually. How to eat less without being hungry is the fix.

When to see a doctor

If you’ve logged everything for a month, weighed every morning, kept your weekends in line, and your trend still hasn’t moved, see your doctor and bring your log and your weigh-ins. In the 1992 study above, the people who were sure their metabolism was the problem had normal metabolisms, so the log is the first thing a doctor will want to see.