Tracking your food and your weight

Weigh yourself every morning and judge the trend over two to four weeks, never one morning. Log your food for at least your first month. Treat a bodyfat scale’s number as a range, and use a tape on your waist as the second check.

Why does my weight go up when I’m doing everything right?

You eat well all week, step on the scale Monday morning, and you’re 3 pounds heavier than Friday. Most people decide something went wrong. Some decide weighing every day makes it worse and stop.

The scale works like a share price. The daily price jumps around for reasons that have nothing to do with how the company is doing, and the trend over months shows whether it’s growing. Your weight each morning includes the food still in you, the water you’re holding, and the glycogen in your muscles, which is stored with three to four times its weight in water. A salty dinner, a carb-heavy weekend or a hard workout can move those by pounds overnight. Your fat moves by a fraction of a pound a week.

Why do I weigh more on Monday?

A European team followed 1,421 adults who weighed themselves on smart scales while trying to keep weight off. Weight rose over the weekend and fell through the week, by about 0.35% on average. For a 200 pound person that’s about 0.7 pounds. Monday was the heaviest day and Friday the lightest. Over Christmas, weight went up by 1.35% on average, and much of it was still there months later.

A 2014 study of 80 adults found the same rhythm. The gain started on Saturday and the fall started on Tuesday, and the pattern was clearest in the people who were losing or holding their weight.

Compare Monday to Monday, or better, this week’s average to last week’s.

Should you weigh yourself every day?

Yes, if it doesn’t upset you. More data points make the trend clear sooner.

People worry that daily weighing breeds anxiety or eating problems. A 2015 review of 17 studies found regular self-weighing went with weight loss and not with depression or anxiety. A 2016 meta-analysis found no link with disordered eating, and a small negative link with how people felt in general. In a six month trial of 91 adults, daily weighers didn’t differ from the others in depression, binge eating or anorexic thoughts, and they were less unhappy with their bodies.

If you’ve had an eating disorder, decide with your care team whether to weigh at all. Your waist, how your clothes fit and photos can stand in for the scale.

How do you know if it’s working?

Why you’re not losing weight goes through the usual causes in order.

Do you need to track your food?

You can lose fat without counting a calorie, and plenty of people do. But almost everyone eats more than they think, and logging for a while shows you where.

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

Logging helps. In a 2008 trial, 1,685 adults went through a six month weight loss program and lost about 13 pounds (5.8 kg) on average. Each extra day a week of food records went with about 1.1 pounds (0.52 kg) more loss, and the study’s press release reported that daily loggers lost twice as much as people who kept no records. A 2011 review of 22 studies found the same link every time, though most of the studies were weak by design.

Labels aren’t exact either. US rules allow a food’s real calories to run up to 20% over the label before it counts as mislabeled. That’s fine for tracking. The error tends to be the same each day, so your log still shows whether you’re eating more or less than last week, and the scale corrects the rest.

• Log everything for a month. Drinks, oil, sauces, bites and tastes, weekends.
• Weigh the calorie-dense foods. Oil, nuts, cheese, peanut butter, rice and pasta are where guesses go furthest wrong.
• Then ease off if you want. Many people keep a few meals they know and only log the new ones.

Are bodyfat scales accurate?

Not for one number. In a 2023 study, researchers tested 15 bioimpedance devices, 14 of them sold for home use, on 73 adults against a lab method that combines three measurements. For a single measurement the total error ran from 3.3 to 12.6 points of bodyfat, depending on the device. If the best of them says 25%, the real number is typically within about 3 points of it, and the worst can be off by far more.

The same researchers brought 37 people back 12 to 16 weeks later. For the change between visits, the total error was 1.9 to 2.9 points. A scale is better at telling you which way you’re going than where you are.

These scales send a small current through your feet and estimate fat from how easily it passes. Water changes that, so the bodyfat number swings with the same water that moves your weight. Weigh at the same time each day, and watch the monthly trend.

Your waist is the other check. The NIH’s heart and lung institute says a waist over 40 inches for men or 35 for women raises your risk of heart disease and type 2 diabetes. Measure at the same spot each time, standing, after breathing out.

Tracking it in Gyroscope

Weigh in each morning on a Withings or any Apple Health scale and Gyroscope logs your weight and bodyfat on its own, free on any plan. Once you have about a month of mornings, watch the trend of your fat mass and lean mass. With Gyroscope One, photograph a DEXA report every few months as the checkpoint, and your coach builds a bodyfat plan from your scale, photos and meals and adjusts it as the number moves. How to track it.