Provider discussing weight gain causes with a patient at Florida Keys Primary Care in Big Pine Key, FL

Unexplained Weight Gain in Big Pine Key, FL: Finding the Root Cause and a Real Solution

Medical workup and personalized weight management from Dr. Gregory Keifer, D.O. and Tabble Memoli, MSN, APRN — serving Middle and Lower Keys families for 40 years.

Common In:Adults 35+, especially women
Treatable:Hormones, thyroid, and metabolism are all testable
Real Tools:GLP-1 medication when clinically indicated
Whole-Person Care:Lifestyle plus medical workup, not shame
Patient and provider reviewing weight gain workup labs in Big Pine Key, FL
Overview

Understanding Unexplained Weight Gain

When the scale is moving and your habits have not changed — there is usually a medical reason

Unexplained weight gain care at Florida Keys Primary Care & Wellness in Big Pine Key, FL begins with a question most providers skip: what changed? If you are eating the same way, exercising the same way, and the scale keeps climbing, the answer is rarely "willpower." It is usually something measurable — and often, something treatable.

Weight gain that does not match your habits points to one of a handful of medical drivers: thyroid changes, hormonal shifts (especially perimenopause and menopause), insulin resistance, certain medications, sleep disruption, or stress-driven cortisol patterns. Our job is to find which one — or which combination — is happening to you.

We use a thorough annual physical exam and targeted lab work as the starting point. If we find a hormonal contributor, we can address it directly through hormone replacement therapy. If you need real, sustained weight loss support, our medical weight loss program includes GLP-1 medications like semaglutide when clinically appropriate. According to the NIDDK, most adults gain 1-2 pounds per year between age 40 and 60 — but a sudden change deserves a real workup.

Hormonal and medical causes of unexplained weight gain
Causes

What's Really Behind Sudden Weight Gain

Sudden or unexplained weight gain almost always has a physiological cause that is testable. The most common drivers are thyroid dysfunction, perimenopause and menopause, insulin resistance and pre-diabetes, certain medications (steroids, antidepressants, beta-blockers), poor sleep, chronic stress, and — for some patients — a slowdown in metabolism that comes with age and muscle loss.

Weight gain is rarely just about weight. It commonly travels with thyroid disorders, hormonal imbalance, menopause and perimenopause, and fatigue and low energy. Treating the underlying driver often does more for the scale than diet alone — which is why we test before we recommend.

Lab workup panel for unexplained weight gain
Learn More

Our Workup and What Treatment Looks Like

The workup for unexplained weight gain is straightforward but thorough. We typically order TSH and free T4 (thyroid), A1C and fasting glucose (insulin resistance and pre-diabetes), a lipid panel, and — depending on age and symptoms — sex hormones (estrogen, progesterone, testosterone, FSH) and cortisol. We also review your medications, sleep, and stress patterns. Most causes show up clearly on this panel, which is part of our preventive care screening.

If the workup points to a thyroid issue, treatment is daily levothyroxine. If it points to perimenopause or hormone imbalance, hormone replacement therapy can be remarkably effective. If insulin resistance or pre-diabetes is the driver — or if you simply need real medical support to lose weight — our medical weight loss program with GLP-1 medications (semaglutide, tirzepatide) offers tools that work where willpower alone has not. Patients on GLP-1s typically lose 10-20% of their body weight over 12-18 months.

For patients with confirmed cardiometabolic conditions, we coordinate weight management with chronic disease management so that diabetes, blood pressure, and cholesterol care all work together — not in silos.

Causes

What Causes Unexplained Weight Gain?

Hormonal

Perimenopause, menopause, and shifts in estrogen, progesterone, or testosterone redistribute and increase body fat.

Thyroid

An underactive thyroid slows metabolism and commonly drives 5-15 pounds of resistant weight gain.

Insulin Resistance

Pre-diabetes and insulin resistance promote fat storage, especially abdominal weight.

Medications

Steroids, certain antidepressants, beta-blockers, and insulin can each contribute to weight gain.

Lifestyle

Disrupted sleep, chronic stress, alcohol, and reduced muscle mass with age all shift the balance.

Why Choose Florida Keys Primary Care for Weight Gain
Why Us

Why Choose Florida Keys Primary Care for Weight Gain

  • Physician Oversight
  • 40 Years of Continuity
  • Lab-Guided Diagnosis
  • Real Medical Tools
  • Local Convenience

Your Weight Gain Care Path at Florida Keys Primary Care

Service Best For Visit Frequency What's Included Goal
Annual Physical Exams First step — workup with full vitals and labs Once per year Thyroid, A1C, lipids, hormone screening, medication review Identify the underlying cause
Medical Weight Loss Programs Patients ready to actively lose weight Monthly visits GLP-1 medications when indicated, nutrition coaching, body composition tracking Sustained weight loss
Hormone Replacement Therapy Perimenopausal or hormone-related weight gain Every 3-6 months Lab-guided HRT, symptom monitoring, body composition support Restore hormonal balance
Chronic Disease Management Weight gain with diabetes, BP, or cholesterol involvement Every 3 months Coordinated metabolic and weight care, integrated medication plan Address the full cardiometabolic picture
Signs You Should Have a Weight Gain Workup
Is This You?

Signs You Should Have a Weight Gain Workup

  • 5+ Pounds Without Lifestyle Changes
  • Weight Gain with Fatigue
  • Weight Gain Around Age 40-55
  • Weight Gain Plus Mood Changes
  • Weight Loss Has Stopped Working
  • Family History of Diabetes or Thyroid
FAQ

Frequently Asked Questions About Unexplained Weight Gain

What causes sudden weight gain?

The most common medical causes are thyroid dysfunction (especially low thyroid), perimenopause and menopause, insulin resistance, certain medications (steroids, beta-blockers, antidepressants), poor sleep, and chronic stress. We test for each of these as part of a standard workup.

Can hormones cause weight gain?

Yes — significantly. Estrogen drops in perimenopause and menopause shift fat storage to the abdomen and lower metabolic rate. Low testosterone in men can also drive weight gain. Hormone replacement therapy, when appropriate, often reverses this.

What tests check the causes of weight gain?

We typically order TSH and free T4 (thyroid), A1C and fasting glucose (blood sugar), lipid panel, comprehensive metabolic panel, and — depending on age and symptoms — sex hormones (estrogen, progesterone, testosterone, FSH) and cortisol. Plus a medication review.

Can thyroid problems cause weight gain?

Yes. An underactive thyroid commonly causes 5-15 pounds of resistant weight gain. Treatment with levothyroxine usually resolves the metabolic slowdown, though weight loss after thyroid is corrected typically still requires lifestyle changes — it just becomes possible again.

Does perimenopause cause weight gain?

Very commonly. Most women gain 5-10 pounds during perimenopause, often around the abdomen, even when eating and activity have not changed. The drop in estrogen alters how fat is stored and burned. HRT, lifestyle adjustments, and sometimes GLP-1 medications all help.

Are GLP-1 medications like semaglutide right for me?

GLP-1 medications (semaglutide, tirzepatide) are highly effective for weight loss in adults with BMI 30+ or BMI 27+ with weight-related conditions like pre-diabetes. They reduce appetite, slow digestion, and boost natural insulin response. We discuss whether they fit your medical history during your visit.

What lifestyle changes help with unexplained weight gain?

Strength training to preserve muscle, prioritizing protein at every meal, getting 7+ hours of sleep, managing stress, limiting alcohol, and reducing refined carbs. These foundations matter — but if there is a hormonal or thyroid driver, lifestyle alone often is not enough, and that is okay.

Location29980 Overseas Hwy
Big Pine Key, FL 33043
Emailoffice@flkeyswellness.com
Phone(305) 872-3321
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Scientific References

  1. PubMed (PMID: 33567185) - Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1 Trial). N Engl J Med. 2021.
  2. PubMed (PMID: 35658024) - Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022.
  3. PubMed (PMID: 23299886) - Davis SR, et al. Understanding weight gain at menopause. Climacteric. 2012.