What was most closely linked to rising blood pressure with weight gain?

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The study examined mechanisms of blood pressure elevation with weight gain, focusing on the contributions of sympathetic nervous system activity, fasting plasma insulin, and leptin to blood pressure levels.

The researchers conducted a longitudinal study of a cohort of 1,897 men. Among those whose body mass index (BMI) rose by more than 10% in the first six months, they measured blood pressure, pulse rate, BMI, and fasting plasma norepinephrine (NE), insulin, and leptin at six and 12 months. This group included 172 lean men with normal blood pressure, 79 obese men with normal blood pressure, 64 lean men with untreated hypertension, and 38 obese men with untreated hypertension.

At study entry, obese participants had significantly higher blood pressure, pulse rate, and plasma NE, insulin, and leptin levels than lean participants, regardless of blood pressure status. Plasma NE, insulin, and leptin levels increased with weight gain in all four groups.

In each group, at both six and 12 months, men whose blood pressure rose had significantly greater increases in pulse rate and plasma NE than men whose blood pressure did not rise, even though their BMI increases were similar. Among obese but not lean participants, whether they had normal blood pressure or hypertension, increases in plasma insulin and leptin with weight gain were greater in those whose blood pressure rose than in those whose blood pressure did not rise. By contrast, at six months among lean participants, the increase in plasma insulin with weight gain was actually lower in those whose blood pressure rose than in those whose blood pressure did not rise.

The researchers said the results suggest that sympathetic overactivity with weight gain is more tightly linked to the accompanying blood pressure elevation than the changes in plasma insulin and leptin. They considered sympathetic nervous system activation with weight gain a probable major mechanism of blood pressure elevation. They also proposed that high insulin and leptin levels may be supporting factors contributing to sympathetic nervous system stimulation with weight gain.