You lost 25 pounds last year. Then, slowly, most of it came back, and you are fairly sure the problem is you. I hear this in our Northborough office nearly every week, from people in Marlborough, Hudson and Sudbury who have been through the cycle three or four times. So let me say the part that rarely gets said: the regain is not a character flaw. It is biology doing what it was built to do.
Your body defends a weight, not a goal
The idea of a set point is simple. Your brain, mostly a region called the hypothalamus, tracks how much stored energy you carry, largely through hormones such as leptin from fat tissue and ghrelin from the stomach. When you lose weight, the brain reads the drop as a shortage and works to restore it. It does not know you lost the weight on purpose. It treats a diet much the way it would treat a famine.
The set point is not fixed for life. It drifts upward with age, poor sleep, certain medications, pregnancy and the food environment we all live in. What it resists is a quick move downward.
What actually changes after you lose weight
Two things happen, and both have been measured.
First, hunger hormones shift and stay shifted. In a study published in the New England Journal of Medicine, researchers followed 50 adults who lost about 30 pounds on a ten-week diet. A full year later, leptin was still low, ghrelin was still high, and participants still reported more hunger than before they started. The appetite signals had not reset.
Second, metabolism slows more than the weight loss alone explains. The clearest example is a National Institutes of Health study of 14 contestants from “The Biggest Loser,” published in the journal Obesity. Six years after the show, their resting metabolism was still roughly 500 calories a day lower than expected for people of their size, and most had regained much of the weight. Researchers call this metabolic adaptation. In everyday terms: after a large loss, you need less food to hold the same weight than someone who was always that size, and you feel hungrier doing it.
Put those two together and the pattern makes sense. Going back to eating “normally” is not neutral. It is a surplus, delivered to a body that is actively asking for more.
Why medication changes the picture, and what happens when it stops
This is also why GLP-1 medicines behave the way they do. They act on the same appetite circuits, so they appear to lower the weight the brain defends rather than asking you to overpower it. It is also why stopping them often undoes the work. In the STEP 1 trial extension, people who stopped semaglutide regained about two-thirds of what they had lost within a year. In SURMOUNT-4, those switched from tirzepatide to placebo regained much of their loss over the following year, while those who continued kept it off. That is not a failure of the medication. It is the set point reasserting itself once the signal is removed, much as blood pressure climbs when someone stops a blood pressure pill.
The Obesity Medicine Association describes obesity as a chronic, relapsing disease. That phrase changes the question from “why can’t I keep it off” to “what does long-term management look like for me.”
How we plan for the pushback at EverWell
Because the body pushes back, we plan for the push.
We measure rather than guess. Labs are drawn on site at the consultation and at follow-ups, so we treat the whole metabolic picture, not the scale alone.
We protect muscle and avoid losing too fast. Rapid loss deepens metabolic adaptation; adequate protein and resistance training blunt it. Giavonna, our registered dietitian, sees EverWell patients one day a week for exactly this kind of planning.
We treat follow-up as part of the treatment. You see the same team at each visit, Courtney Laperriere, PA-C, Diana Kisel, FNP-C and me, working from one chart. Established patients in Massachusetts can do many follow-ups by telehealth, which keeps frequent check-ins realistic for someone commuting from Southborough or Hudson.
And we talk about maintenance at the first visit, not after the regain starts, because the time after the loss is where most diets quietly end.
When to talk to a clinician rather than read on
If you have regained weight you worked hard to lose, if your hunger feels out of proportion to what you eat, or if your weight is affecting your blood pressure, blood sugar, sleep or joints, it is worth a visit rather than another attempt on your own.
Now reserving new-patient spots for spring 2027 — we’re moving to a larger, modern office in Marlborough. Reserve your EverWell consultation with the short form on our new-patient page or call (508) 770-6701 — our team will call you within one business day to confirm your details and save your place, and patients on our list get first choice of appointment times. You can read more about the program on our EverWell page. Current patients: our office is at 162 Main Street, Northborough.
Gunardi Irawan, MD, is board-certified in internal medicine and obesity medicine and leads a primary care and medical weight-management practice in Northborough, Massachusetts. This article is general health information, not medical advice for any individual.
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