Biomarkers · Anthropometric

Body Mass Index (BMI)

Both low and high values go with higher risk of death. In NHANES 1999–2018 with linked mortality to 2019, each standard deviation above average goes with 3% higher risk of death. Risk rises at both ends: not comparable

BMI and risk of death

NHANES, our fit with 95% CIPublished curve

Published curve higher than the NHANES fitNHANES fit higher

Risk of death relative to each curve's own reference value, so the two curves need not cross 1 at the same point. The dotted vertical line marks the NHANES median.

Risk of death per SD (NHANES)1.03×95% CI 1.00–1.06 · 50,698 adults, 7,280 deaths

Published risk of death1.45×obesity grade 1 (BMI 30.0-<35.0 kg/m2) vs BMI 22.5-<25.0 kg/m2 (grade 2: 1.94… (95% CI 1.41–1.48) · IPD meta-analysis of 239 prospective studies (10,625,411 participants, 4 continents); primary analysis 3,951,455 never-smokers without chronic disease who survived 5 years

Value of the measurement+0.012gain in concordance within age bands; rank 31 of 56 · all tests

Across studies, risk per SD1.03×NHANES 1.03 [1.00–1.06] · CRELES 1.10 [0.95–1.28] · HRS 1.04 [1.01–1.08]

BMI across cohorts

0.750.80.911.11.25HR per SD (95% CI)

NHANES · United States, 20–8450,698 people · 7,280 deaths1.03 1.00–1.06

CRELES · Costa Rica, 60+2,386 people · 434 deaths1.10 0.95–1.28

HRS · United States, 50+23,342 people · 8,108 deaths1.04 1.01–1.08

CHARLS · China, 50+10,345 people · 1,682 deaths0.81 0.75–0.88

Risk-of-death ratio per standard deviation, adjusted for age and sex, within each cohort. Cohorts differ in age range, assay, measurement protocol and follow-up, and one SD is a different amount in each, so the comparison is of direction and rough size per SD, not per unit. Vertical line: no association.

BMI by age and sex

Each bar runs from the 5th to the 95th percentile, the darker part from the 25th to the 75th, and the tick is the median. Not a reference range or a target.

The percentiles as a table

Each row is one sex and age band: the values below which 5%, 25%, 50%, 75% and 95% of people fall (kg/m2), from the survey named in the row. Not a reference range or a target.
Sex	Age	5th	25th	Median	75th	95th	n	Cycle / source
All	20-39	19.1	23.5	27.8	33.5	43.5	1,523	NHANES 2017-2018
All	40-59	20.6	25.4	29.1	34.0	44.6	1,634	NHANES 2017-2018
All	60+	20.8	25.4	28.8	33.4	40.6	1,963	NHANES 2017-2018
All	all	20.0	24.7	28.6	33.6	43.5	5,120	NHANES 2017-2018
Men	20-39	19.4	23.8	27.9	33.2	41.2	729	NHANES 2017-2018
Men	40-59	22.4	26.2	29.6	33.7	42.2	770	NHANES 2017-2018
Men	60+	21.3	25.8	28.6	33.0	39.3	994	NHANES 2017-2018
Men	all	20.8	25.2	28.9	33.4	41.7	2,493	NHANES 2017-2018
Women	20-39	19.0	22.8	27.2	33.7	45.5	794	NHANES 2017-2018
Women	40-59	19.5	24.2	28.6	34.7	47.0	864	NHANES 2017-2018
Women	60+	20.7	25.1	28.9	33.7	42.5	969	NHANES 2017-2018
Women	all	19.7	24.0	28.4	34.0	45.0	2,627	NHANES 2017-2018

What studies found when this marker was changed

They describe what happened in those study groups, not a recommendation. See all catalogued interventions.

Measured changes in BMI, study by study

9 effects with a numeric size, each from one study arm: the dot is the reported change, the line its 95% interval where one was given. Study results in the groups studied, not predictions for a person.

Each row is one study: what was changed, the effect it reported on this marker, and the source.
Type	Intervention	Reported effect	Evidence	Source
diet	Increase daily dietary fibre by ~15 g or to 35 g/day without other lifestyle change in adults with prediabetes or diabetes	BMI reduced by 0.36 kg/m2 (95% CI -0.55 to -0.16) vs lower-fibre diets	meta-analysis	Reynolds AN, Akerman AP, Mann J. PLoS Med. 2020.
diet	Low-carbohydrate high-fat ketogenic diet for a mean of ~16 weeks in women with lipedema	BMI fell by 4.23 kg/m2 (95% CI 2.49 to 5.97) pre- to post-intervention after a mean 15.85 weeks of LCHF diet	meta-analysis	Amato ACM, Amato JLS, Benitti DA. Nutrients. 2024.
exercise	Physical-activity-only interventions for preventing obesity in children aged 6-12 years	BMI reduced by 0.10 kg/m2 (95% CI -0.14 to -0.05) in 6-12 year olds	meta-analysis	Brown T, Moore TH, Hooper L, et al. Cochrane Database Syst Rev. 2019.
exercise	Exercise training vs control in adults with type 2 diabetes and obesity (network meta-analysis of 32 RCTs)	BMI fell 1.78 kg/m2 (95% CI -2.70 to -0.85) with exercise vs control; duration not stated; 32 RCTs; combined aerobic-resistance training ranked best	meta-analysis	Xu J, et al. Front Immunol. 2026;17:1825473.
lifestyle	Combined diet, physical activity and behavioural programmes in women with polycystic ovary syndrome	BMI reduced by 0.34 kg/m2 (95% CI -0.68 to -0.01) vs minimal treatment	meta-analysis	Lim SS, Hutchison SK, Van Ryswyk E, et al. Cochrane Database Syst Rev. 2019.
pharmacologic	GLP-1 receptor agonists vs placebo in overweight or obese adults with moderate-to-severe obstructive sleep apnea (network meta-analysis)	BMI fell 1.78 kg/m2 (95% CI -2.15 to -1.41) vs placebo; duration not stated; network meta-analysis of 15 studies	meta-analysis	Zheng J, et al. Front Endocrinol (Lausanne). 2026;17:1869479.
pharmacologic	Metformin vs placebo to prevent weight gain in people with schizophrenia taking antipsychotics (Cochrane review)	Metformin limited the BMI increase by 1.63 kg/m2 (95% CI -2.96 to -0.29) vs placebo; duration not stated; 5 studies, n=227	meta-analysis	Agarwal SM, et al. Cochrane Database Syst Rev. 2022;10:CD013337.
pharmacologic	Anti-obesity medications vs control for maintaining weight loss in adults with overweight or obesity (12 RCTs)	BMI fell a further 3.58 kg/m2 (95% CI -5.69 to -1.46) vs control during weight-loss maintenance; duration not stated; 12 RCTs	meta-analysis	Chen Z, et al. Diabetes Obes Metab. 2026;28(10):8913-8924.
supplement	Calcium supplementation vs placebo or control in people with overweight or obesity (Cochrane review)	BMI fell 0.18 kg/m2 (95% CI -0.22 to -0.13) vs placebo or control; duration not stated as a single value (trials of eight weeks to 24 months); 9 studies, n=731	meta-analysis	Cormick G, et al. Cochrane Database Syst Rev. 2024;5:CD012268.

What else moves this marker

They describe those study groups, not an individual, and an association is not a cause.

Genetic predisposition

Each row is one study: what it compared and the change it reported in this marker.
What	Effect on the marker	Comparison · population	Source
↑ ADRB3 Trp64Arg (beta3-adrenergic receptor) · Trp64Arg variant carriers vs normal homozygotes	+0.3 kg/m2 (95% CI 0.13 to 0.47)	variant carriers (n=2447) vs non-carriers (n=6789) · 48 subgroups from diverse populations	meta analysis · PMID 9661625

Environmental and occupational exposures

Each row is one study: what it compared and the change it reported in this marker.
What	Effect on the marker	Comparison · population	Source
↑ Maternal active smoking in pregnancy (child BMI) · child BMI z-score at age 6-11, active maternal smoking vs no smoking	SMD +0.28 (95% CI 0.09 to 0.48)	active maternal smoking vs no smoking in pregnancy · HELIX study, children aged 6-11 from six European birth cohorts	prospective cohort · PMID 32579081
↑ Smoking cessation (quit between age 21 and 38) · smokers at 21 who had quit by 38 vs continuing smokers at 38	+1.5 kg/m2	quitters vs continuing smokers at age 38 · Dunedin birth cohort (New Zealand), followed age 15-38	prospective cohort · PMID 24463712

Sources

Risk curve: Global BMI Mortality Collaboration (Di Angelantonio E 2016 (PMID 27423262): all-cause HR 1.45 (1.41-1.48) obesity grade 1 (BMI 30.0-<35.0 kg/m2) vs BMI 22.5-<25.0 kg/m2 (grade 2: 1.94 [1.87-2.01]; grade 3: 2.76 [2.60-2.92]; BMI 15.0-<18.5: 1.51 [1.43-1.59]). Scaled to published population values.
Global BMI Mortality Collaboration (Di Angelantonio E, et al.). Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents. Lancet. 2016;388(10046):776-786.
NHANES curve: our Cox model adjusted for age and sex, NHANES 1999–2018 with linked mortality to 2019.

Map Body Mass Index (BMI) against another biomarker · Featured: HbA1c × body mass index.

Map BMI against another marker