Metformin: Drug That Lowers Insulin and Insulin Resistance (But Prevents Exercise-induced Muscle Growth and VO2 Max Benefits)
Until recently the mechanism of action of metformin was unknown. Recent studiessuggest that metformin affects LKB1 which activates and increases AMPK activity. We have discussed earlier AMPK as it’s role is important in conserving proliferation and growth per demand and for the purpose of energy production. Simply put, AMPK increases fat uptake into peripheral cells, fat burning, and mitochondrial biogenesis in muscles upon energetic demands (e.g. when ATP goes down at the cellular level). When I used to counsel patients on metformin, I added sometimes that metformin is like ‘exercise in a pill’ — it results in lower glucoses, lower insulin resistance, reduction in adiposity, lowering of inflammation, and weight loss. Unlike starvation and exercise, however, metformin generally does not induce eventual hunger (in fact it can induce nausea and anorexia). Metformin apparently has no hypothalamus AMPK effects, and this is perhaps why hunger does not ensue despite weight loss associated with metformin. Other notable effects of metformin are — GI upset, nausea, diarrhea, unpredicted ‘explosive’ diarrhea (as several patients have complained to me), abdominal cramping, intestinal dysbiosis leading to clinical vitamin B12 deficiency and related cognitive deficits over time.