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Study Links Weight Gain in Early Adulthood to Higher Mortality Risk

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Early Adulthood Weight Gain Linked to Higher Risk of Premature Death, Major Swedish Study Finds

A large, long-term study from Lund University in Sweden has found an association between weight gain during early adulthood and a higher risk of premature death from various causes, including cardiovascular disease, type 2 diabetes, and some cancers. The research, published in the journal EClinicalMedicine, analyzed weight trajectories and mortality data for over 620,000 individuals in Sweden.

"The lowest mortality risk was observed with modest weight gain of 0–0.25 kg per year."

Study Methodology

The research, part of the Obesity and Disease Development Sweden (ODDS) pooled cohort study, involved 258,269 men and 361,784 women. Researchers modeled continuous weight trajectories using repeated weight measurements taken between the ages of 17 and 60. The key age points analyzed were:

  • 17 years: The start of adulthood
  • 29 years: The end of young adulthood
  • 60 years: The start of older adulthood

The median follow-up period was 23 years for men and 12 years for women. During this time, 86,673 men and 29,076 women died. The median age of death was 77 years for men and 78 years for women. Critically, most weight measurements were taken by staff in healthcare settings rather than self-reported.

Key Findings on Weight and Mortality

Weight Gain Patterns

  • The median weight change was 0.42 kg per year between ages 17 and 60.
  • The median total weight gain during this period was 18 kg for men and 17 kg for women.
  • Weight gain was generally faster in younger years, particularly among men, and slowed later in life.

Mortality Risk

  • All-cause mortality was higher among individuals who gained weight more rapidly, became obese as young adults, or gained considerable weight between ages 17 and 29.
  • The association was stronger for weight gained in early adulthood compared to weight gained later in life.
  • With a weight gain of 0.5 kg/year between ages 17 and 29, all-cause mortality increased by 18% in men and 16% in women.
  • Individuals who became obese between ages 17 and 29 had an approximately 70% higher risk of early death compared to those who did not become obese before age 60. Men in this category had a 69% higher risk, and women a 71% higher risk.

Cause-Specific Disease Associations

Cardiovascular Disease

  • Cardiovascular disease accounted for 37% of excess deaths.
  • Weight gain in early adulthood showed a strong association with mortality from cardiovascular diseases.

Type 2 Diabetes and Hypertension

  • Strong associations were found between weight gain and mortality from type 2 diabetes and hypertension.

Cancer

  • Cancer mortality accounted for 31% of deaths.
  • The strongest cancer-specific associations were with liver cancer in men and uterine cancer.
  • In women, cancer risk was associated with weight gain across age groups, not solely early adulthood. Researchers suggested hormonal changes may play a role.
  • In men, early adulthood weight gain showed a stronger association with cancer mortality than later weight gain.

Other Diseases

  • Weight gain was also linked to mortality from diseases of the liver and kidneys.

Sex Differences

  • Men gained weight most rapidly in early adulthood, while women had more stable weight gain rates between ages 17 and 29.
  • The proportion of obese individuals increased with age in both sexes.
  • In women, weight gain at any age appeared to increase cancer risk, a pattern not observed to the same degree in men.

Study Limitations

The researchers noted several limitations of the study:

  • The observational nature of the study means causality cannot be inferred.
  • The study could not distinguish between deliberate and inadvertent weight loss.
  • Important confounding factors such as diet, physical activity, and comorbidities were not fully captured.
  • Unmeasured confounding is possible, though the researchers stated it is unlikely to fully explain the observations.
  • Risk figures represent relative risk and may be influenced by the factors accounted for in the study and measurement accuracy.

"A negative control analysis using brain cancer did not show an association, suggesting the results are robust against major spurious bias."

Research Context

The authors noted that previous research on cause-specific mortality and weight change often used only two measurement points. This study used multiple weight measurements across adult life. A negative control analysis using brain cancer did not show an association, suggesting the results are robust against major spurious bias. The weight gain patterns observed in the Swedish study population were described as similar to those in typical Western populations.