Losing 40 kg is likely to take more than a year for most patients. Our endocrinologists typically observe three to four kilos a month on treatment, and weight loss often slows over time. In SURMOUNT-1, a Phase 3 clinical trial of tirzepatide, patients on the highest dose lost an average of around 20% of their body weight over 72 weeks. Your endocrinologist will set a realistic target from your starting weight and review it with you month by month.
- Forty kilos in a year requires around 3.3 kg a month for twelve months in a row, and weight loss often slows as the months go on.
- Resting metabolic rate decreases as you lose weight, which is one reason later months are often slower than early ones.
- The US prescribing information for Zepbound reports that a little over half of participants on the highest dose in the SURMOUNT-1 clinical trial lost 20% or more of their body weight over 72 weeks.
- A useful first milestone is losing 5–10% of your starting weight over six months, as recommended by the NIDDK. You can then review the next stage with your doctor.
- Most adults with 40 kg to lose meet the BMI threshold for weight loss medication, which is a BMI above 30, or above 27 with a weight-related condition.
- Adequate protein and resistance training can help preserve muscle over a long weight loss phase.
- How much loose skin develops varies with factors such as age, starting weight, the amount of weight lost and skin elasticity.
Losing 40 kg is one of the largest targets patients discuss at a first consultation. A realistic timeline depends on the monthly rate of weight loss, which often slows over time.
How long does it take to lose 40 kg?
Endocare’s endocrinologists typically observe weight loss of three to four kilos per month in patients on a medically supervised programme, and that rate often slows as the months go on. The table below converts common timeframes for a 40 kg target into the monthly rate each one requires. It compares that rate with what we typically observe and with the gradual rate of 0.5 to 1 kg a week, roughly two to four kilos a month, described by the US Centers for Disease Control and Prevention (CDC).
| Timeframe for 40 kg | Monthly rate required | How it compares |
|---|---|---|
| 6 months | Around 6.7 kg a month | Well above the rate our endocrinologists typically observe |
| 12 months | Around 3.3 kg a month | Within the observed range, but only if that rate holds for a full year |
| 18 months | Around 2.2 kg a month | Within the gradual rate the CDC describes, with room for slower months |
| 24 months | Around 1.7 kg a month | A slower pace that leaves room for plateaus |
A 12-month timeframe matches the rate we typically observe, and it also requires that rate to continue for a full year. Many patients do not sustain that rate, because weight loss often slows. Our article on how much weight you can lose in a month explains why the early months are often faster.
The prescribing information for Zepbound, the weight management version of tirzepatide approved by the US Food and Drug Administration (FDA), reports that participants in the SURMOUNT-1 clinical trial started at an average of around 105 kg. A little over half of those on the highest dose lost 20% or more of their body weight over 72 weeks. Forty kilos is more than 20% of body weight for anyone starting below 200 kg.
Why does a gradual pace help on a 40 kg plan?
A larger calorie deficit can increase lean-mass loss and is generally harder to sustain over time. A study in the International Journal of Obesity measured a decrease in resting metabolic rate of around 101 calories a day in adults who lost around 8 kg over a year. It attributed roughly 60% of that decrease to the loss of energy-expending tissue and roughly 40% to metabolic adaptation.
The National Institute of Diabetes and Digestive and Kidney Diseases states that losing weight very quickly may raise your chances of forming gallstones, and that experts recommend beginning with a weight loss of 5 to 10% of your starting weight over six months. For a 40 kg target, that first milestone is a useful checkpoint with your endocrinologist before the plan is extended.
What protects muscle while you lose fat?
Protein
Adequate protein and resistance training can help preserve muscle while you lose weight. A review in the journal Nutrients concluded that higher protein intakes help protect fat-free mass and skeletal muscle mass during weight loss, either on their own or together with exercise. General guidance such as the International Society of Sports Nutrition suggests roughly 1.2 to 1.6 g of protein per kg of body weight per day for people losing weight. Endocare’s lifestyle coaches will personalise that figure from your body composition analysis.
Resistance training
A retrospective study of 304 adults on a calorie-restricted diet, published in Frontiers in Endocrinology, found that resistance training produced the greatest reduction in fat mass and was the only form of exercise associated with an increase in fat-free mass. Two to three sessions a week can help preserve muscle during weight loss, and the sessions can start at home. At Endocare, body composition analysis is included free of charge at every consultation. Body composition analysis estimates body fat, muscle mass and body water. Repeated measurements help your endocrinologist understand how your body is changing beyond the number on the scale.
What changes when a doctor is involved?
Our endocrinologists prescribe weight loss medication for patients with a body mass index above 30, or above 27 where there is a weight-related condition such as type 2 diabetes, hypertension or high cholesterol. Most adults with 40 kg to lose meet those criteria, and our article on who qualifies for weight loss injections explains the assessment.
The options our endocrinologists prescribe range from weekly injections, Mounjaro, Wegovy and Ozempic, to the daily tablets Foundayo and the Wegovy pill. In STEP 1, a Phase 3 clinical trial in adults with obesity or overweight, patients taking the Wegovy injection at 2.4 mg lost an average of around 15% of their total body weight over 68 weeks. On a 40 kg plan, the dose and sometimes the medication change over time, and your endocrinologist will review both with you.
Monthly follow-up appointments can be held in person at the clinic or online. We recommend the first consultation in person, as it includes a physical examination and body composition analysis. Patients should not decide by themselves to start a GLP-1 medication. A doctor’s review is critical to ensure the treatment is safe and appropriate for the individual.
Will losing 40 kg leave loose skin?
How much loose skin develops varies with factors such as age, starting weight, the amount of weight lost and skin elasticity. Some patients notice changes in skin tone or firmness after losing 15 kg, while significant excess skin is more common after larger amounts of weight loss. Loose skin is therefore a realistic possibility after a 40 kg loss.
Skin laxity may improve gradually after weight stabilises, although how much it improves varies. Whether any further treatment is appropriate is a decision for after your weight has been stable for some time. Our article on loose skin after weight loss explains the options and their limits.
Which plateaus should you expect?
Plateaus are expected on a 40 kg plan. Short-term changes on the scale are often influenced by body water, alongside normal day-to-day variation.
We do not recommend responding to a weight loss plateau by immediately cutting calories further. A larger calorie deficit can be harder to sustain and may increase the risk of losing lean mass. Instead, our coaches typically review the plan, maintain adequate protein intake and allow more time before making further adjustments. If your weight is not changing despite a consistent plan, it may be worth reviewing both the plan and whether any medical factors could be contributing. Our article on why you may not be losing weight on Mounjaro covers what your endocrinologist reviews at a follow-up.
How do you keep 40 kg off?
Keeping a large loss off is part of the plan from the start. At Endocare, patients slowly reduce the dose or lengthen the time between injections as advised by their doctor, continue lifestyle coaching, and stay in contact with the clinic. Regain is possible if the underlying causes of weight gain are not addressed. Lifestyle coaching is designed to address them.
Our article on keeping it off after a GLP-1 medication explains what protects the result once treatment ends. Some patients set a smaller first target on the way to 40 kg, which our article on how to lose 20 kg in 6 months covers.
Frequently asked questions
How long does it take to lose 40 kg?
For most patients, it is likely to take more than a year. Forty kilos over a year requires around 3.3 kg a month for twelve months in a row, and weight loss often slows as the months go on. Your endocrinologist will give you a timeframe based on your starting weight and your response.
Is it possible to lose 40 kg in a year?
For some patients, it may be. It requires around 3.3 kg a month for a full year, which matches the rate our endocrinologists typically observe, although many patients do not sustain it for a full year. The US prescribing information for Zepbound reports that a little over half of participants on the highest dose of tirzepatide in the SURMOUNT-1 clinical trial lost 20% or more of their body weight over 72 weeks.
Will I get loose skin?
Loose skin is possible after a 40 kg loss. Significant excess skin is more common after larger amounts of weight loss, and how much develops varies with factors such as age, starting weight, the amount of weight lost and skin elasticity.
Do I qualify for weight loss injections at this weight?
Most adults with 40 kg to lose meet the BMI criteria. Your endocrinologist will still review your medical history, your medications and your blood tests before prescribing, because eligibility also depends on what is safe for you.
How long would 40 kg take on Mounjaro?
There is no fixed answer, because the response to Mounjaro is individual. In SURMOUNT-1, a Phase 3 clinical trial, patients taking tirzepatide, the active ingredient in Mounjaro, at the highest dose lost an average of around 20% of their total body weight over 72 weeks. Importantly, this average weight loss was measured over 72 weeks. Your endocrinologist will set a realistic timeframe with you and review it at each monthly follow-up.
What happens when I stop losing weight?
Your endocrinologist will review the plan with you. We do not recommend responding to a weight loss plateau by immediately cutting calories further. Instead, our coaches typically review the plan, maintain adequate protein intake and allow more time before making further adjustments.
If you have 40 kg to lose, the first step is a consultation. Your endocrinologist will assess your starting point and your body composition analysis, and agree the first milestone and the review schedule with you.
You can talk to an endocrinologist at our clinics in Dubai and Abu Dhabi.
