Abstract Obesity presents a metabolic burden that leads to increased non-communicable disease (NCD) morbidity with metabolic syndrome (MS) as a pathway. The aim was to examine the trends in the obesity and MS prevalences. The study included health examination survey data collected in 2000 and 2023 (n = 7 258, 20-64 years). Examination measurements, blood samples, questionnaires, and register data were collected. MS criteria (ATPIII/AHA) included at least 3 of the following: increased waist circumference, elevated fasting glucose or medication, elevated triglyceride or medication, elevated blood pressure (BP) or medication, and decreased HDL-cholesterol or medication. Participants were divided according to BMI (normal weight 18.5-24.9 kg/m2, overweight 25.0-29.9 kg/m2, obesity 30.0-34.9 kg/m2, severe obesity = >35.0 kg/m2). Weighted prevalence and 95% confidence intervals (CIs) of MS and obesity were calculated considering sampling design and non-response. Prevalences of normal weight decreased from 2000 (men 32%, 95% CI 30-35; women 45%, 95% CI 43-47) to 2023 (men 26%, 95% CI 23-28; women 34%, 95% CI 32-37) and obesity increased from 2020 (men 17%, 95% CI 15-18; women 15%, 95% CI 14-17) to 2023 (men 20%, 95% CI 18-22; women 18%, 95% CI 16-20) as did severe obesity (in 2000: men 4%, 95% CI 3-5; 6%, 95% CI 5-7 - in 2023 men10%, 95% CI 8-12; women 13%; 95% CI 11-14). The prevalence of MS increased from 37% (95% CI 34-39) to 45% (95% CI 43-48) in men and 30% (95% CI 28-32) to 37% (95% CI 34-39) in women. The prevalence of MS with obesity varied from 2000 to 2023 from 73-77% in men and 69-61% in women and with severe obesity from 88-91% in men and 79-76% in women. From 2000 to 2023, no MS components remained stable with normal weight (men 29-25%, women 44%) and obesity (both sexes <1%). The prevalence of MS has increased in the last 20 years. Obesity is a major risk factor for MS that increases the future burden MS and, consequently, of NCD on societies. Key messages • Metabolic syndrome has increased in Finland from 2000 to 2023. At the same time, the prevalence of those with normal weight has decreased and severe obesity increased. • The global obesity pandemic will further increase the burden of NCD’s in the future. This is already visible with increasing metabolic syndrome prevalence.