Your goal weight of 80 kg (176 lb) has been on the display for three weeks. Today the scale says 81.4 kg (179.5 lb), and the diet is over. If you want to keep weight off after a diet, set a corridor around your goal weight, weigh yourself regularly and act when your trend weight leaves the corridor. One high daily reading is no reason to act. A corridor of 1.5 percent above and below is a workable start: at 80 kg it runs from 78.8 to 81.2 kg (173.7 to 179.0 lb).
Why maintaining is harder than losing
While you lose weight, a target sits in front of you. While you maintain, that target is gone after the first day. The numbers are sobering: about 20 percent of people with overweight keep a loss off long term. Discipline explains only part of that. Rosenbaum and Leibel (2010) describe that energy expenditure falls further after weight loss than the lost body mass predicts. Researchers call this adaptive thermogenesis. Your body burns less than that of someone who has always weighed 80 kg, so a maintenance intake you remember from before the diet may be too high.
How large the effect is for you cannot be calculated in advance. You see it in the curve: if your trend rises on an intake that used to hold steady, your needs have dropped.
What people who keep the weight off do
Wing and Phelan (2005) summarize what people have in common who hold a loss for years. Three habits show up:
- They check their weight regularly.
- They are active about one hour per day.
- They eat breakfast.
Data from the National Weight Control Registry back the first point: according to Grief and Miranda (2010), 75 percent of members weigh themselves at least once a week. Both sources describe groups. They do not prove that each habit works on its own. Weighing is the habit that is easiest to measure and automate, and it gives you the early warning: you fix a small drift with a small change, while a large one calls for another diet.
A corridor instead of a single number
A single target value turns 80.6 kg into a failure and 79.8 kg into a success, although both readings can belong to the same trend weight. The reasons for these swings are in Why your weight fluctuates every day. A corridor builds the normal scatter in and flags only the deviation that counts.
How wide it should be depends on how early you want to be warned. A narrow corridor of 0.5 percent triggers early and often. A wide one of 5 percent allows 4 kg of drift at 80 kg. At 1.5 percent you sit in between:
| Goal weight | 1.5 percent | Corridor |
|---|---|---|
| 60 kg (132 lb) | 0.9 kg (2.0 lb) | 59.1 to 60.9 kg |
| 80 kg (176 lb) | 1.2 kg (2.6 lb) | 78.8 to 81.2 kg |
| 100 kg (220 lb) | 1.5 kg (3.3 lb) | 98.5 to 101.5 kg |
The lower limit should not sit in the underweight range. The WHO lists the BMI classes.
Reading the corridor in the trend
Trendcurve has a maintain mode for this. You set the goal to "Maintain", either through the "Maintain now" offer in the goal celebration or through the corridor card in the "Goal" tab. The corridor starts at 1.5 percent around your goal weight. You can set it between 0.5 and 5 percent or as a fixed amount. Trendcurve draws it as a band in the chart and shows a status that tells you whether your trend weight is inside. Band and status are free.
What matters is what you read against the band. A daily value of 81.4 kg is outside the corridor, while a trend weight of 80.5 kg sits in the middle: you do nothing. How this smoothed value comes about is explained in Trend weight instead of the daily value. A deviation begins when the trend line itself reaches the limit.
Pro adds the corridor history. It shows the days inside the corridor, the share over 30 and 90 days and the longest streak. After three months you know how stable your maintenance was and do not have to guess.
When the trend leaves the corridor
Your trend weight is 80.6 kg and rises by 0.3 kg (0.7 lb) per week, as the 7-day change shows. The upper limit of 81.2 kg is 0.6 kg away, so you reach it in two weeks. You are still inside the corridor and already have a reason to act.
The early warning in Pro covers exactly this case. It sends a notification and shows a banner in the "Today" tab when the trend leaves the corridor or would leave it within 14 days at the current rate. It fires at most once per direction in 14 days. Without Pro, you read the 7-day change yourself and divide the distance to the limit by the weekly rate.
The warning extends the current rate forward. It knows nothing about your holiday next week, and a few days of heavy salt or hard training can bend the rate for a short time. Treat it as a hint, not a verdict.
React in small steps. Change one habit, for example the evening portion or your daily steps, and judge the result after two weeks on the trend, not on single mornings. If the trend sits at 80.4 kg two weeks later and the rate is 0.1 kg per week, the change works and you keep it. If you take medication or have an illness that affects your weight, discuss changes with your doctor.
Pick a fixed weekday on which you check the distance between your trend weight and the upper and lower limit. If that distance is smaller than what the trend covers in two weeks, change one habit that day.