Tirzepatide in Asian Adults: What SURMOUNT-CN and SURMOUNT-J Show About Weight Loss at Lower BMIs

Tirzepatide in Asian adults produced weight loss in the same percentage range seen in the global trials, according to two phase 3 studies run entirely in Asian populations. In SURMOUNT-CN, Chinese adults lost an average of 13.6% of body weight on tirzepatide 10 mg and 17.5% on 15 mg over 52 weeks, compared with 2.3% on placebo, while in SURMOUNT-J, Japanese adults lost 16.1% (10 mg) and 21.1% (15 mg) more than placebo over 72 weeks.

Those trials matter because many Asian adults carry higher metabolic risk at a lower body mass index (BMI) than people of European descent, so participants started out lighter than those in the original SURMOUNT program.

How much weight do Asian adults lose on tirzepatide?

Asian adults in the two dedicated phase 3 trials lost roughly 14% to 21% of body weight on tirzepatide, depending on dose, trial length and how each trial reported its result. SURMOUNT-CN, published in JAMA by Zhao and colleagues, ran at 29 centers in China and randomized 210 adults without diabetes to once weekly tirzepatide 10 mg (n=70), 15 mg (n=71) or placebo (n=69), each alongside a lifestyle program, for 52 weeks.

The SURMOUNT-CN participants were relatively young, with an average age of 36.1 years and an average BMI of 32.3.

SURMOUNT-J, published in The Lancet Diabetes & Endocrinology by Kadowaki and colleagues, compared tirzepatide 10 mg and 15 mg with placebo for 72 weeks in Japanese adults without diabetes. The analysis population of 225 had an average age of 50.8 years, and SURMOUNT-J reported its main result as the difference from placebo, and at week 72 weight fell 16.1% more on 10 mg and 21.1% more on 15 mg than on placebo.

The global SURMOUNT-1 trial also included 102 Japanese adults, and a prespecified analysis found average weight change at week 72 of 12.0% on 5 mg, 22.4% on 10 mg and 22.1% on 15 mg, compared with 0.3% on placebo. The group is small, so those results carry wide uncertainty.

Does tirzepatide work the same in Asian and non-Asian adults?

The percentage of body weight lost on tirzepatide appears broadly similar in Asian and non-Asian trial populations, although no trial has been designed to prove they are the same. A 2026 systematic review pooled five SURMOUNT trials with 4022 participants, two of them fully Asian, and found placebo adjusted loss on the top dose of 18.16% in the Asian trials and 17.92% in the predominantly non-Asian trials.

The authors noted that the comparison "cannot confirm equivalence." Absolute loss was larger in the non-Asian trials (23.46 kg versus 16.72 kg), which the authors attributed mostly to higher starting weight, so people who start lighter lose fewer kilograms for the same percentage drop.

Why are BMI cutoffs different for Asian adults?

BMI cutoffs are lower in many Asian guidelines because metabolic risk tends to rise at a lower BMI in Asian populations. A WHO expert consultation published in The Lancet in 2004 concluded that a substantial proportion of Asian people have high risk of type 2 diabetes and cardiovascular disease at BMIs under 25, with the point where risk began to climb varying from 22 to 25 across populations. It proposed public health action points at BMIs of 23.0, 27.5, 32.5 and 37.5 rather than one new cutoff.

A cohort of 1,472,819 adults in England looked for the BMI at which type 2 diabetes risk matched the risk at BMI 30 in White adults, and that equivalent BMI was 23.9 in south Asian adults and 26.9 in Chinese adults.

This difference is the reason the Asian trials used lower entry thresholds than SURMOUNT-1. Japan defines obesity disease as starting at a BMI of 25 with excess fat accumulation, according to the Japanese Society for the Study of Obesity.

Who qualifies for tirzepatide in the US if they are Asian American?

In the US, eligibility for Zepbound follows the FDA label, which covers adults with obesity, or adults with overweight plus at least one weight related condition, alongside a reduced calorie diet and more physical activity. The label does not set separate BMI thresholds by ethnicity, and its pivotal trial enrolled people with a BMI of 30 or higher, or 27 to under 30 with a weight related condition; about 11% of those participants were Asian.

Some Asian Americans may carry metabolic risk similar to someone heavier while falling below those thresholds, so if you are unsure whether you meet the criteria, a licensed clinician can review your full health history, including waist size and metabolic markers, and tell you whether any treatment is appropriate. Our guide to who qualifies for tirzepatide covers the US criteria in more detail.

Does waist size matter more than BMI for Asian adults?

Waist size can add useful information beyond BMI, especially for people whose weight sits in the normal or overweight range on standard charts. In a post hoc SURMOUNT-CN analysis of 177 participants that used Chinese specific cutoffs, 37 people reached a normal BMI by Chinese criteria (18.5 to 24) by week 52, and in that group the share meeting criteria for metabolic syndrome fell from 21.6% to 0%. Being post hoc, this shows association rather than cause, and our article on tirzepatide and visceral fat covers central fat.

What happens after Asian adults stop tirzepatide?

People in SURMOUNT-CN regained a meaningful share of weight after stopping tirzepatide, although most stayed below their starting weight over the following 26 weeks. A follow up by Chen and colleagues tracked 152 participants after treatment ended at week 52.

From the point of stopping, the former 10 mg group regained 9.1% of body weight and the former 15 mg group regained 12.3%, compared with 1.8% in the former placebo group. Measured from the start of the trial, net change at week 78 was still 8.7% and 10.6% below baseline in the former tirzepatide groups. This was an observational follow up, but it fits the pattern described in our article on weight regain after stopping GLP-1 therapy.

Are tirzepatide side effects different in Asian adults?

Side effects in the Asian trials resembled those in the global program, with gastrointestinal symptoms the most common. In SURMOUNT-CN most events were mild to moderate and fewer than 5% of participants stopped treatment because of them, while in SURMOUNT-J adverse events were reported by 84% of people on 10 mg and 86% on 15 mg, compared with 69% on placebo. The US label starts at 2.5 mg weekly for 4 weeks and increases in 2.5 mg steps. The same label carries a boxed warning about thyroid C-cell tumors, and tirzepatide is contraindicated in people with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Other labeled warnings include acute pancreatitis and acute gallbladder disease, the label states that tirzepatide may cause fetal harm and should be stopped when pregnancy is recognized, and a clinician reviews these risks before prescribing.

What can't the Asian tirzepatide trials tell us yet?

The Asian trials answer the core weight question, but several gaps remain. The numbers are small, since the two trials contributed only 148 tirzepatide treated people to the pooled analysis, and they studied Chinese and Japanese adults, so evidence for south Asian, Southeast Asian, Korean, Filipino and other populations is limited. The trials also measured markers rather than heart attacks or new diabetes diagnoses, and few people with a BMI between 23 and 25 have been studied, so benefits and risks in that range are not established.

Frequently Asked Questions

The Bottom Line

The trials in Chinese and Japanese adults show tirzepatide producing weight loss in the same percentage range as the global studies, with a familiar side effect profile. What differs is the starting point, because Asian adults often carry metabolic risk at a lower BMI. If you are unsure whether you meet the criteria, a licensed clinician can review your full health history, including waist size and metabolic markers, and tell you whether any treatment is appropriate. Individual results vary.

Sources

• Zhao et al., JAMA, 2024 (SURMOUNT-CN), doi:10.1001/jama.2024.9217.
• Kadowaki et al., Lancet Diabetes & Endocrinology, 2025 (SURMOUNT-J), doi:10.1016/S2213-8587(24)00377-2.
• Japanese subpopulation analysis of SURMOUNT-1, Obesity, 2026, doi:10.1002/oby.70131.
• Systematic review and meta-analysis, Endocrinology, Diabetes & Metabolism, 2026, doi:10.1002/edm2.70291.
• Chen et al., Life Metabolism, 2025 (SURMOUNT-CN follow up), doi:10.1093/lifemeta/loaf024.
• SURMOUNT-CN post hoc analysis, Obesity, 2025, doi:10.1002/oby.24306.
• WHO Expert Consultation, The Lancet, 2004, doi:10.1016/S0140-6736(03)15268-3.
• Caleyachetty et al., Lancet Diabetes & Endocrinology, 2021, doi:10.1016/S2213-8587(21)00088-7.
• FDA, Zepbound (tirzepatide) prescribing information, 2026, accessdata.fda.gov.