Mouse Study: Kratom Reduces Breathing Rate and Increases Weight Gain in Obese Animals at High Doses

Why it matters

This study raises the largely unstudied question of how obesity changes how the body responds to kratom — a critical gap given that many kratom users in the United States may be overweight or have metabolic conditions.

The big picture

Most kratom research has focused on healthy-weight subjects, leaving open questions about how the substance affects those with obesity or metabolic disorders. As kratom use becomes more widespread, understanding its cardiovascular and metabolic effects in diverse populations becomes increasingly important for both clinicians and regulators.

Key findings

• Kratom extract and mitragynine reduced respiratory rate approximately 15% in obese mice at all tested doses
• Unlike alprazolam (a known respiratory depressant), kratom did not reduce total minute ventilation
• High-dose kratom (500 mg/kg) reduced heart rate ~12% in normal-weight mice
• Daily high-dose kratom (150 mg/kg) increased body weight gain by approximately 1 gram in the final week of dosing
• After kratom cessation, the high-dose group showed reduced locomotor activity in anxiety testing

What they say

The authors concluded that the results "demonstrate a dose-dependent increase in weight gain with [kratom extract], suggesting further investigation is needed to delineate kratom alkaloid effects on metabolism and body weight control."

Bottom line

**High-dose kratom slows breathing rate and may promote weight gain in obese mice — pointing to a need for human studies in metabolically vulnerable populations.**