When weight gain happens despite your best efforts, there's often an underlying metabolic cause. Lab tests can help identify what's really going on.
Common Causes of Unexplained Weight Gain
- Hypothyroidism: Low thyroid slows metabolism
- Insulin resistance: High insulin promotes fat storage
- PCOS: Hormonal imbalance affecting metabolism
- Cortisol imbalance: Chronic stress and belly fat
- Estrogen dominance: Fluid retention and fat storage
- Medication side effects: Many meds cause weight gain
The Weight Investigation Lab Panel
Thyroid
- TSH, Free T3, Free T4
- Thyroid antibodies
- Reverse T3
Metabolic
- Fasting insulin (the key test many doctors skip)
- Fasting glucose
- HbA1c
- Lipid panel
- Uric acid
Hormones
- Testosterone (women with high levels store more belly fat)
- DHEA-S
- Estrogen and progesterone
- Morning cortisol
Inflammation
- hs-CRP
- Ferritin
The Insulin Connection
Insulin is your fat storage hormone. Even with normal glucose, high insulin:
- Promotes fat storage
- Blocks fat burning
- Increases hunger and cravings
Fasting insulin is the most sensitive test but is often not ordered.
References
- Biondi, B. (2010). Thyroid and obesity: an intriguing relationship. Thyroid, 20(4), 413-415.
- Reaven, G. M. (2005). The insulin resistance syndrome: definition and dietary approaches to treatment. Annual Review of Nutrition, 25, 391-406.
