Could my hormones be causing my fatigue, mood swings, and weight gain?

Yes — and this combination of symptoms is one of the most common presentations in functional medicine. Hormones regulate energy production, mood stability, metabolism, and body composition simultaneously, which is why imbalances tend to produce multiple symptoms at once rather than isolated ones.

The hormones most commonly involved in this pattern include:

• Cortisol — dysregulated cortisol drives fatigue, mood instability, blood sugar swings, and abdominal weight gain simultaneously
• Thyroid hormones (T3/T4) — low thyroid function slows every metabolic process in the body, producing fatigue, weight gain, depression, and cognitive slowing
• Estrogen and progesterone — imbalances between these two hormones drive mood instability, sleep disruption, weight changes, and fatigue, particularly in perimenopause
• Testosterone — low testosterone in both men and women produces fatigue, mood changes, reduced motivation, and difficulty maintaining lean muscle mass
• Insulin — insulin resistance is a hormonal condition that drives weight gain, energy crashes, and mood instability through blood sugar dysregulation

The key is comprehensive hormone testing that goes beyond a basic TSH or estradiol level. Patterns matter more than individual numbers — a hormone can be "in range" and still be contributing to symptoms if it is at the wrong end of the range or imbalanced relative to another hormone.

A functional medicine evaluation maps the full hormonal picture and identifies which pattern is driving your specific symptom cluster.