Why the scale lies in the first two weeks of a diet

Everyone loses weight quickly at the start of a diet and almost nobody is told why, which sets up an entirely avoidable disappointment in week three. Here is what is actually happening, and the one test that tells you whether the plan is working.

When you cut refined carbohydrate and processed food, you draw down stored glycogen, the carbohydrate your muscles and liver keep on hand. Glycogen is stored with water, roughly three grams of it for every gram of glycogen; that ratio was measured in the 1970s and confirmed again in 2015. Salt intake usually falls at the same time, which sheds more water. Between the two, the scale can move several pounds in ten days. None of it is fat, and all of it comes back after a large plate of pasta.

This does not mean the early loss was fake or that you did something wrong. It means the fast part is over and the real rate is now becoming visible. Roughly half a percent to one percent of bodyweight a week is a rate most people can sustain while holding on to their muscle. For a 180-pound person that is somewhere under two pounds a week, and the lower half of that range is usually the better place to live. In athletes, losing at about 0.7 percent a week preserved and even added lean mass where losing twice as fast did not. People who do not know any of this quit at week three, convinced it stopped working, when what actually happened is that it started.

The scale is also a moody instrument on any given day. Your weight can swing three or four pounds inside twenty-four hours on food volume, salt, hydration and where you are in your week, and none of that is fat either. A person who weighs daily and reacts to each reading is responding almost entirely to noise. Two ways to use it sensibly: weigh once a week under the same conditions and compare weeks, or weigh daily and look only at the weekly average. Both work. Daily weighing with daily emotional consequences does not.

Then the test. Weigh yourself under the same conditions for three weeks and compare the average of week one with the average of week three. Not day to day; averages, three weeks apart. If the number has come down slightly, you are in a deficit and the plan is working. If it is flat, you are at maintenance. If it has gone up, you are in a surplus. That is the whole test, and it is more reliable than any calorie equation, because it measures you rather than estimating a population. Three weeks is not arbitrary: it is long enough for the water, the glycogen, the salt and the ordinary randomness of a body to average out. Two weeks is not, which is why people who judge at two weeks conclude their metabolism is broken.

The scale is one instrument on a dashboard. Watch what you can lift and for how many reps. Watch how clothes fit around the waist, and measure the waist monthly, because it often moves when the scale will not. Notice whether four in the afternoon is a crisis or a non-event, and how you sleep. Lifts going up while the scale holds still is one of the best outcomes available to you; it usually means you are trading fat for muscle, and a scale cannot tell you that.

Chapter seven of The LP3 Diet is the fat-loss chapter. It has no calorie number in it, on purpose, and this test is the reason it does not need one.