Realistic Weight Loss per Week: How Much Can You Lose?

How much weight can you lose in a week?

How much weight you can lose in a week, at a pace that tends to stay off, is about 1 to 2 pounds (0.5 to 1 kg) for most adults. The CDC says people who lose "at a gradual, steady pace" of 1 to 2 pounds a week are more likely to keep it off, and the NHS gives the same range in kilograms.

The first week is the exception. It's often several pounds, and most of that is water (more below). And whatever your weekly rate is in month one, it'll be slower in month six.

Two single weigh-ins can't tell you your rate. Daily weight swings by a pound or more on its own, so you need the slope of a trend over a few weeks. If you're new to that idea, here's what trend weight is and how it works, or paste your numbers into the weight trend calculator to see your weekly rate.

Is 2 pounds a week realistic?

For a lot of people, yes, at least for a while. But it's the top of the range, not the middle, and how hard it is depends on your size.

The NIDDK (part of NIH) doesn't give a weekly figure at all. It suggests a first goal of 5 to 10% of your starting weight within six months. For someone at 200 pounds that's 10 to 20 pounds in six months, which averages under a pound a week. The CDC adds that even 5% can improve blood pressure, cholesterol and blood sugar.

Thinking in percent helps. Two pounds is 1.5% of body weight at 130 pounds but under 0.7% at 300. There's no official percent target, but sports nutrition research often works this way: in a trial in athletes, those losing about 0.7% a week gained lean mass while a 1.4% group didn't.

Here's what 0.5 to 1% a week looks like at different weights. It's arithmetic for illustration, not a prescription.

If you're on the lighter side and keep missing a 2-pound target, the target is probably the problem, not you.

Why is the first week so much faster?

Because the first few pounds are mostly water. You store carbohydrate as glycogen in your liver and muscles, held with three to four parts water for every part glycogen. Eat less, especially fewer carbs, and you draw that store down. The water leaves with it.

It works in reverse too. A carb-heavy weekend refills the glycogen and the water comes back, which looks like sudden regain. Lose four pounds in week one, "gain" two after a pasta dinner: same mechanism.

So don't use week one to predict month three. Start measuring from week two or three.

Why does weight loss slow down over time?

A smaller body uses less energy, so the same eating pattern creates a smaller deficit as you go. Kevin Hall's group at NIH modelled this in a 2011 Lancet paper. Their rule of thumb for an average adult with overweight: each lasting cut of about 10 calories a day eventually moves your weight by about a pound, with half of that change reached in about a year and nearly all of it in about three.

So a steady 250-calorie daily cut might eventually take off around 25 pounds, fastest at the start and tapering after that. It doesn't keep going at the same weekly rate. That's also why the old "3,500 calories per pound" rule overpromises beyond the first few weeks.

Slowing down is normal. It's not the same as stalling completely, though the two can look alike; here's how to tell a plateau from water retention.

How do you work out your actual rate?

Use the slope of your trend over three to four weeks, not the gap between two mornings.

An illustrative example: you weigh 182.4 lb one Monday and 180.0 lb the next. That looks like 2.4 pounds in a week. But if the first Monday followed a salty dinner and the second followed a long run, half that gap could be water. A trend that smooths every weigh-in in between might show 182.0 falling to 181.1, about 0.9 lb a week. That's the number to plan around.

For a slope you can trust, weigh under the same conditions each time, often enough for the average to settle (daily is ideal if it doesn't stress you), and divide the trend's change over three or four weeks by the number of weeks. Periscope's Reports tab shows this as a rate of change per week next to a smoothed trend line.

Frequent weighing isn't for everyone. If it makes you anxious, or you have a history of disordered eating, it's fine to weigh less often or not at all; NEDA (US) and Beat (UK) offer support.

How do you plan a realistic timeline?

Use the NIH Body Weight Planner. It's built on the same model as the Lancet paper, so it allows for the slowdown instead of drawing a straight line. Enter your details, a goal and a date, and it estimates the calories to get there and to maintain afterwards. It also flags plans that would push intake below 1,000 calories a day.

Try a longer date first. If three months needs a cut you know you won't keep up, see what six months asks. After a month, compare its projection with your trend and adjust the plan if they're far apart.

When is a rate too fast?

Mostly when it stays fast after the first couple of weeks. A pace well above 2 pounds (or about 1% of body weight) a week usually means a very large deficit. The NHS notes that very low calorie diets aren't suitable or safe for everyone. If you're losing quickly and can't explain why, see a doctor.

Slow is rarely a problem. Half a pound a week is 26 pounds in a year.

Sources

1. CDC. Steps for Losing Weight.
2. NHS. Obesity: overweight and obesity in adults.
3. NIDDK. Choosing a Safe & Successful Weight-loss Program.
4. NIDDK. Body Weight Planner.
5. Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. Am J Clin Nutr. 1992.
6. Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011.
7. Garthe I, et al. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011.