How to Weigh Yourself for Useful Trends

One reading on a scale is a snapshot. What is useful is the pattern across weeks, and getting a clean pattern depends on weighing yourself the same way each time. This guide covers set-up, timing, how often to weigh, how to read the numbers and when to step back. It is general information for adults, not medical advice. For the buying checks, see our guide to choosing a smart scale.

Why a single weight is noisy

Body weight moves in a rhythm. A 2014 study in Obesity Facts by Orsama and colleagues analyzed 4,657 daily weights from 80 adults and found higher weight early in the week, on Sunday and Monday, falling through the week. Increases began on Saturday and decreases on Tuesday. The authors concluded that differences between weekends and weekdays should be regarded as normal, not as signs of weight gain, and the pattern was strongest in people who lost or maintained weight.

A 2020 paper in PLoS One by Turicchi and colleagues followed people taking part in a European weight-maintenance trial and found a within-week fluctuation of 0.35%, with weekend gain and weekday reduction. Over Christmas, weight rose by a mean of 1.35% and was not fully compensated for in the following months. These are group patterns from the studies' own samples, so your rhythm will vary. A 0.35% swing is about half a pound for a 155 lb adult (our arithmetic).

Set up the scale the same way every time

• Place. Garmin's manual says to use its scale on a hard, flat floor for the most accurate weight. Pick one spot and leave the scale there.
• Feet. Garmin's guidance for body-composition readings is to remove socks and shoes, stand still with your feet flat on the glass and keep the surface dry. Standing the same way helps for plain weight too.
• Clothes. Weigh in the same state each time, for example before dressing. This is our suggestion rather than a published rule.
• Time. Garmin asks you to use the scale under the same circumstances and at about the same time of day. For body-composition readings it recommends waiting two hours after eating, drinking, exercising, bathing or visiting a sauna.

If you do not have a scale yet, a plain one is enough for weight alone: digital bathroom scales on Amazon (opens in a new tab) is a search for them.

How often to weigh yourself

The CDC's page on losing weight describes a gradual, steady pace of about 1 to 2 pounds a week, says people who lose weight this way are more likely to keep it off, and suggests asking a health care provider for follow-up visits to monitor changes in your weight. It does not set a weighing schedule, and the research does not name a single ideal interval either. A 2015 systematic review and meta-analysis by Madigan and colleagues found only one trial of self-weighing on its own, with no evidence that it was effective (an average of 0.5 kg less weight, with a confidence interval from 1.3 kg less to 0.3 kg more, which includes no effect). When self-weighing was part of a larger program, weight loss was greater, and there was no significant difference between weekly and daily weighing instructions. A 2015 review by Zheng and colleagues of 17 longitudinal studies of adults seeking weight-loss treatment found that regular weighing was associated with more weight loss, and not with adverse psychological outcomes such as depression or anxiety. Those findings come from people trying to lose weight, describe associations, and do not cover everyone.

So choose a pattern you can keep without it taking over your day. Weekly is simple and works against the daily rhythm described above. Daily is workable if you look at the average rather than each number.

Reading the pattern

• Compare like with like. Compare the same weekday, or averages of whole weeks. In the Orsama study the early-week peak is part of the normal pattern.
• Use averages. If you weigh daily, add up a week's readings, divide by the number of readings and compare that figure with the previous weeks. Garmin's trend graph shows one value a day, using the last reading if you weigh more than once.
• Look at weeks, not days. At the CDC's pace of 1 to 2 pounds a week, a change shows over several weeks, long after a half-pound weekly wobble has averaged out.
• Do not chase one result. Holiday weeks, illness and travel can move the number, and Garmin's manual notes that activities can temporarily affect your body's weight, hydration and distribution of water.

If you use a calculator to set an energy target, treat it as an estimate. Our calorie calculator says its result is an estimate and not a substitute for nutrition counseling.

Using the other numbers on a smart scale

Body-fat and muscle estimates are less reliable than weight; in a French hospital study three smart scales read fat mass too low by medians of 2.2 kg, 4.4 kg and 3.7 kg compared with a DEXA scan, and the authors concluded that smart scales are not accurate for body composition. Our guide to what bioimpedance scales can and cannot measure covers this. If you log them, log them under identical conditions and watch the direction over several weeks. A waist measurement is a useful cross-check; see BMI, waist and body-fat numbers explained. A body measuring tape on Amazon (opens in a new tab) is a search for one.

When to step back

• Weighing is affecting you. The National Institute of Mental Health says some people become fixated or obsessed with weight loss, body weight or shape, and that this may be a sign of an eating disorder, which it says can be treated successfully. If checking the scale feels compulsory or leaves you distressed, stop and talk to a doctor. Withings offers an Eyes-Closed Mode that hides readings on the scale's screen, but hiding numbers does not replace advice from a clinician. If you are in crisis, call or text 988.
• You are pregnant. The CDC advises working with your health care provider on weight gain goals and tracking weight regularly through pregnancy, and Withings says its scale has not been tested and/or validated for use then. Ask your provider how and how often to weigh.
• It is for a child. The CDC says children's BMI is read against sex-specific percentiles for age and is a screening measure, not a diagnosis. If you are worried about a child's weight, talk to their pediatrician rather than weighing at home.
• You have a condition that affects fluid or weight, or an implanted device. Ask your doctor or clinic how and how often to weigh yourself, and see our buying guide for the pacemaker advice that makers and the American Heart Association give.

A simple routine

Put the scale on a hard floor in one spot, weigh yourself at the same time of day in the same state, write the number down or let the app log it, and judge by weekly averages over a month or more. Keep a tape measure beside it for the waist. Search for a body composition scale on Amazon (opens in a new tab) only if you want the extra estimates, and check the manual for the safety notes first.

Your scale's manual is the authority on how to use it, and your doctor or pharmacist is the right person to ask if you have a health condition.