There are several ways in which BMI may influence longevity and the risk of premature death. Excess body fat is a well-established risk factor for cardiovascular disease, including coronary heart disease and stroke, increasing risk through elevated cholesterol and triglyceride levels, high blood pressure, low-grade inflammation, and insulin resistance. These factors not only contribute to chronic illness but can also shorten lifespan.
As ever, please talk to your doctor, or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle; especially if you are under treatment. Relevant studies are shared at bottom of page.
The Risks of Being Overweight
Obesity is the strongest known risk factor for type 2 diabetes, which is associated with a two to threefold increase in mortality risk. It is also linked to at least 10 different cancers, including oesophageal (adenocarcinoma), liver, gallbladder, colorectal, pancreatic, kidney, advanced prostate, postmenopausal breast, endometrial and ovarian cancer. Some evidence suggests an association with other cancers, such as thyroid cancer, leukaemia, multiple myeloma and lymphomas, as well as poorer survival rates after a cancer diagnosis - further impacting longevity.
Several biological mechanisms may explain these links, including the hormonal effects of adipose tissue, insulin resistance, chronic inflammation, and the role of obesity in conditions such as gastro-oesophageal reflux disease, gallbladder disease and colorectal adenomas. Additionally, excess body fat can weaken immune function, further influencing disease progression and lifespan.
Beyond cancer and cardiovascular disease, obesity is linked to a wide range of chronic conditions that can reduce healthspan and longevity. However, being underweight may also pose risks, increasing susceptibility to chronic lung disease and other respiratory conditions. In some cases, this may be due to reverse causality, as unintentional weight loss can signal the progression of chronic obstructive pulmonary disease, and smoking is strongly linked to these conditions.
What is a Healthy BMI?
Studies on BMI and longevity suggest a J-shaped dose-response relationship with all-cause mortality, meaning that both overweight and underweight individuals face increased risks.
Research indicates that the lowest mortality rates occur in those with a BMI of 23-24 among never-smokers and 22-23 among healthy never-smokers.
With longer follow-ups, the optimal BMI range appears to be between 20-22. However, there is some evidence of increased mortality in underweight individuals, though this may partly result from confounding errors due to pre-existing illness.
Longevity advocate Bryan Johnson, who follows a strict health optimisation regimen, maintains a BMI of 22.8, within the range associated with the longest lifespan.
Final Thoughts
BMI is only one factor in longevity, and individual health outcomes depend on multiple influences, including genetics, lifestyle, and overall metabolic health. While maintaining an optimal BMI may contribute to a longer, healthier life, it should be considered alongside other key factors such as diet, exercise, and disease prevention.
For most people improving health - achieving a healthy weight - is about finding motivation and prioritising self-care with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle, The Whole Health Practice is here to help.
Whether your interest is in balance or longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.
Our foundational Whole Health Consult identifies and prioritises the key factors - known and unknown - that affect health and wellbeing. It provides targeted recommendations tailored to you, the individual, and your unique lifestyle.
Stay Healthy,
Alastair
Join me, or scroll down to contact us and learn more about our services:
Achieve your Health and Weight Goals
Your health, physical – mental – social - is complex and affected by multiple factors within and outside of your control. Our consults and programmes address the whole person, the root causes of ill health and maximising your health, performance & vitality.
Take the first step. Contact us to arrange an introductory call, to discuss how we can support your journey to health. We are based in Singapore and work with clients globally.
Book a Whole Health Consult to assess, identify and prioritise key factors (known and unknown) that affect your health. And receive personalised recommendations on how to address them.
Want to put recommendations into action? Learn more about our programmes for individuals or teams.
Related Resources and Studies
Singapore HealthHub, BMI, info and calculator
UK NHS, BMI calculator
Tham KW, Lim AYL, Baur LA. The global agenda on obesity: what does this mean for Singapore? Singapore Med J. 2023 Mar;64(3):182-187. doi: 10.4103/singaporemedj.SMJ-2023-018. PMID: 36876624; PMCID: PMC10071858.
Ni X, Su H, Lv Y, Li R, Liu L, Zhu Y, Yang Z, Hu C. Modifiable pathways for longevity: A Mendelian randomization analysis. Clin Nutr. 2023 Jun;42(6):1041-1047. doi: 10.1016/j.clnu.2023.04.026. Epub 2023 May 5. PMID: 37172463.
Larsson SC, Burgess S. Causal role of high body mass index in multiple chronic diseases: a systematic review and meta-analysis of Mendelian randomization studies. BMC Med. 2021 Dec 15;19(1):320. doi: 10.1186/s12916-021-02188-x. PMID: 34906131; PMCID: PMC8672504.
Bhaskaran K, Dos-Santos-Silva I, Leon DA, Douglas IJ, Smeeth L. Association of BMI with overall and cause-specific mortality: a population-based cohort study of 3·6 million adults in the UK. Lancet Diabetes Endocrinol. 2018 Dec;6(12):944-953. doi: 10.1016/S2213-8587(18)30288-2. Epub 2018 Oct 30. PMID: 30389323; PMCID: PMC6249991.
Global BMI Mortality Collaboration, Di Angelantonio E, Bhupathiraju ShN, Wormser D, Gao P, Kaptoge S, Berrington de Gonzalez A, Cairns BJ, Huxley R, Jackson ChL, Joshy G, Lewington S, Manson JE, Murphy N, Patel AV, Samet JM, Woodward M, Zheng W, Zhou M, Bansal N, Barricarte A, Carter B, Cerhan JR, Smith GD, Fang X, Franco OH, Green J, Halsey J, Hildebrand JS, Jung KJ, Korda RJ, McLerran DF, Moore SC, O'Keeffe LM, Paige E, Ramond A, Reeves GK, Rolland B, Sacerdote C, Sattar N, Sofianopoulou E, Stevens J, Thun M, Ueshima H, Yang L, Yun YD, Willeit P, Banks E, Beral V, Chen Zh, Gapstur SM, Gunter MJ, Hartge P, Jee SH, Lam TH, Peto R, Potter JD, Willett WC, Thompson SG, Danesh J, Hu FB. Body-mass index and all-cause mortality: individual-participant-data meta-analysis of 239 prospective studies in four continents. Lancet. 2016 Aug 20;388(10046):776-86. doi: 10.1016/S0140-6736(16)30175-1. Epub 2016 Jul 13. PMID: 27423262; PMCID: PMC4995441.
Aune D, Sen A, Prasad M, Norat T, Janszky I, Tonstad S, Romundstad P, Vatten LJ. BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants. BMJ. 2016 May 4;353:i2156. doi: 10.1136/bmj.i2156. PMID: 27146380; PMCID: PMC4856854.
Fontana L, Hu FB. Optimal body weight for health and longevity: bridging basic, clinical, and population research. Aging Cell. 2014 Jun;13(3):391-400. doi: 10.1111/acel.12207. Epub 2014 Mar 14. PMID: 24628815; PMCID: PMC4032609.
Comments