A fresh investigation suggests that not merely gaining weight, but the timing of that weight gain, impacts our lifelong health, with an increase in weight during early adulthood showing a stronger correlation to mortality risk. The findings of this study have been published in the journal eClinicalMedicine.
Participants for whom obesity initially manifested between the ages of 17 and 29 were approximately 70 percent more likely to pass away from any cause during the follow-up period, compared to those who had not developed obesity by the age of 60.
The research, conducted by a team at Lund University in Sweden, was focused on tracking weight fluctuations over time rather than relying on single snapshot data points. Information concerning over 600,000 individuals was drawn from an existing dataset, specifically including only those with a minimum of three recorded weight measurements between the ages of 17 and 60.
While the study does not prove that early weight gain was the direct cause of the deaths, rather than some other confounding element, we are aware that obesity is implicated in numerous health complications.
“The most consistent takeaway is that gaining weight in youth is connected to a greater risk of premature death later in life, in contrast to individuals who accumulate less weight,” states epidemiologist Tanja Stocks from Lund University.
The researchers hypothesize that the cause of earlier mortality might stem from a prolonged exposure to the biological strain induced by excess weight, where the body endures greater pressure and faces an increased risk of wear and tear beyond the norm.
The research group monitored overall mortality rates and deaths linked to multiple obesity-related conditions, including cardiovascular disease, several cancer types, and type 2 diabetes.
Obesity was defined as the first registered Body Mass Index (BMI) value reaching 30 or higher. At the time the weight measurements were taken, BMI assessment was standard procedure, but obesity definitions are subject to ongoing revision.
Beyond the core finding regarding early adult weight gain, several other associations deserve mention. As would be anticipated, those who experienced the greatest overall weight gain across all age cohorts exhibited a higher probability of death during the study period.
Cardiovascular ailments, such as heart attacks and strokes, accounted for the largest proportion of these associations.
“Our findings indicating higher all-cause and cardiovascular mortality linked to weight gain early in life and the onset of obesity suggest that the key risk factor may not be the amount of weight gained in late adulthood, but rather the duration of obesity,” the researchers note. “Prolonged exposure to insulin resistance, inflammation, and hypercoagulability, all driven by adipocytokines released from adipose tissue, likely contributes to the emergence of these risks.”
Deaths related to type 2 diabetes and certain cancers were also associated with obesity; however, no statistically significant link was established for some causes of death, including bladder cancer in men and stomach cancer in women.
Disparities also surfaced between male and female participants.
Regarding cancer among women, the elevated risk of premature death linked to obesity was roughly equivalent regardless of when the weight increase occurred. This implies that a different factor, perhaps hormonal shifts related to menopause, plays a more significant role here than in other health outcomes.
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“If what we found in women reflects what happens around menopause, then we must ask: which came first, the chicken or the egg?” questions epidemiologist Huyen Le from Lund University. “It’s possible that hormonal changes affect weight, as well as the timing and duration of these changes, and the weight merely reflects what is happening internally.”
Limitations must be acknowledged here. Physical activity and diet were not factored in and could very well have influenced the mortality figures observed by the researchers—factors known to be critical for overall well-being.
The study authors point out that incorporating data on these factors could be a path for future research, as could investigating fat distribution, which modern obesity definitions address, along with distinguishing between fat mass and muscle mass.
Nevertheless, given the substantial number of participants and the multi-year tracking of each individual’s weight, the researchers believe these discoveries are vital for public health: obesity prevention efforts should commence as early as possible.
To quantify the mortality risk uncovered: If approximately 10 out of every 1,000 participants without early obesity passed away within the follow-up duration, about 17 out of 1,000 died in the cohort who developed obesity early on.
“One should not become overly fixated on the exact risk figures,” advises Stocks. “They are seldom completely precise because they are influenced by variables like the factors accounted for in the study and the accuracy of measuring both the risk factors and the outcomes. However, understanding these patterns is crucial, and this research sends an important message to decision-makers and policymakers.”
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