Unexplained Weight Gain: What Blood Tests to Request

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.