Why has my weight loss slowed down?

Because a smaller body burns fewer calories, so the same diet makes a smaller gap each week. On top of that, the body trims its burn a little more than its new size explains. Re-set your calories every 10 to 15 pounds, keep moving through the day, and expect the pace to slow.

What’s going on

When you started, your diet was, say, 500 calories under what you burned. Twenty pounds later you burn less, so the same food might be only 300 under. Nothing broke. The gap shrank.

It’s like a car that gets better mileage as you unload it. Fill it with the same gas each week, and the tank empties more slowly.

How big the slowdown is

• The size effect. A 2011 model from NIH scientists found that each 10 calories a day you cut, for good, takes about 1 pound off in the end, with half of it gone in about a year. The loss tapers by design.
• The extra slowdown. People who keep off 10% or more of their weight burn about 10 to 15% less than their new size predicts, about 300 to 400 calories a day, according to a 2010 review.
• The extreme case. Six years after The Biggest Loser, 14 contestants burned about 500 calories a day less at rest than their size predicted. That was after losing over 100 pounds on a TV show, far beyond an ordinary diet.

The part you can control

Everyday movement outside the gym varies a lot from person to person. In a 1999 study, 16 adults ate 1,000 extra calories a day for 8 weeks. The ones whose everyday movement rose the most gained the least fat. A daily walk and fewer hours sitting help keep the gap open.

What to do

1. Re-set your calories with the calories to lose calculator at your new weight.
2. Walk every day and keep lifting.
3. If you’ve dieted for months, plan a stretch at maintenance before the next push. See how long to diet before taking a break.