From Thyroid to Stress: 13 Hidden Reasons Behind Unexplained Weight Gain

Weight gain can happen for many complex reasons that go far beyond calorie counts. Dr. Naomi Parrella, an obesity medicine specialist and family physician at Rush University, explains that statistically, gaining one to two kilograms per year between the ages of 20 and 65 can be considered normal. But if the increase is more than that, it might be linked to less obvious factors.