Why can’t I lose weight even though I diet and exercise?

By Sina Hartung, MMSC-BMI, Harvard Medical SchoolReviewed by Eureka Health Medical Group
Published: July 9, 2025Updated: July 9, 2025

Summary

A persistent weight plateau is usually caused by hidden calorie gaps, metabolic adaptation, sleep or stress hormones, or medical issues such as thyroid dysfunction and insulin resistance. Tight food tracking, strength training, seven hours of sleep, and targeted lab tests often uncover the barrier. If weight has not changed for 12 weeks despite an evidence-based plan, speak with a clinician or use Eureka’s AI doctor to screen for treatable causes.

Could my body be adapting to my calorie deficit?

After 4–6 weeks of dieting, the body often burns fewer calories by unconsciously moving less and slowing resting metabolism. This survival response is called adaptive thermogenesis and explains why an initial 500-kcal deficit may shrink to 100–200 kcal over time.

  • Resting energy can drop by 10–15 % within weeksStudies in the National Weight Control Registry show average resting metabolic rate falls 78 kcal/day after two months on a 25 % calorie deficit.
  • Non-exercise activity thermogenesis dwindlesPeople fidget and stand less when calories are low, silently erasing 200–300 kcal per day.
  • Strength training protects lean massTwo 30-minute full-body sessions per week prevent up to 60 % of the metabolic slowdown by conserving muscle.
  • Protein pushes metabolism slightly higherEating 1.6 g/kg of body weight in protein raises the thermic effect of food by roughly 80 kcal daily.
  • Expert insight“Plateaus are rarely about willpower; they’re about physiology. Increasing step count from 6 000 to 10 000 can restart loss without cutting more food,” says Sina Hartung, MMSC-BMI.
  • Exercise calories are partly cancelled by energy compensationA 2021 analysis using doubly labeled water found that only about 72 % of exercise energy shows up in total daily expenditure because the body suppresses other energy-costly processes, leaving roughly 28 % “missing.” (UChicago)
  • Increasing workout time beyond 150 min/week can overcome plateausMayo Clinic notes that topping the basic 150 minutes of moderate or 75 minutes of vigorous activity each week—sometimes even doubling it—helps counter the metabolic slowdown that stalls weight loss. (Mayo)

References

When do unexplained weight stalls signal an underlying medical problem?

If you are truly in an energy deficit yet weight or waist size will not budge for three months, a hidden medical or medication-related cause should be ruled out promptly.

  • TSH above 4 mIU/L hints at hypothyroidismLow thyroid slows basal metabolism; treatment can restore a 150–300 kcal daily burn.
  • Fasting insulin over 15 µIU/mL suggests insulin resistanceHigh insulin locks fat in storage and can increase hunger signals.
  • SSRIs, beta-blockers and steroids add 2–5 kg in a yearUp to 25 % of patients on paroxetine gain more than 7 % of baseline weight.
  • Obstructive sleep apnea triples leptin levelsPoor oxygenation disrupts appetite hormones and keeps cortisol high.
  • Doctor’s note“Any rapid gain in the face of a healthy lifestyle deserves thyroid, cortisol, and medication review,” adds the team at Eureka Health.
  • PCOS-linked insulin resistance can block fat lossWebMD notes that polycystic ovary syndrome affects about 6–10 % of women and drives insulin resistance, making weight reduction difficult even with calorie restriction. (WebMD)
  • Metabolic rate falls as weight drops, erasing earlier calorie gapsMayo Clinic explains that a plateau appears when energy burned matches intake because resting metabolism slows with each kilogram lost, requiring further dietary or activity adjustments. (Mayo)

References

Which daily habits can I adjust right now to restart fat loss?

Fine-tuning routine variables often restarts the scale without drastic dieting. Focus on objective tracking, sleep hygiene, and stress control.

  • Weigh food for one full weekPeople under-report intake by 20 % on average; a digital scale reveals hidden calories.
  • Aim for 7–9 hours of sleepShort sleep raises ghrelin 14 % and increases next-day calorie intake by about 300 kcal.
  • Walk 8 000–10 000 steps every dayConsistent light movement burns an extra 200–400 kcal compared with sedentary days.
  • Prioritize high-volume, low-energy foodsFilling half the plate with vegetables drops meal energy density below 1 kcal/g while preserving fullness.
  • Perspective from the field“Tracking fiber, not just calories, keeps hunger in check and predicts who maintains weight loss,” notes Sina Hartung, MMSC-BMI.
  • Strength-train 3–4 times weekly to preserve lean massSpecimen Training recommends 3–4 short (30–45 min) sessions built around compound lifts, which helps drive fat loss without sacrificing muscle. (Specimen)
  • Trim alcohol to improve sleep and calorie controlDigital Barbell flags excessive drinking as a common fat-loss roadblock, noting that reducing alcohol intake supports recovery and reduces empty calories. (DBF)

References

Which lab tests and medications often uncover or correct hidden weight barriers?

Targeted blood work and medication review identify treatable physiologic hurdles. Results determine whether lifestyle tweaks or medical therapy is needed.

  • Comprehensive metabolic panel plus lipidsElevated ALT or triglycerides can signal fatty liver, which slows fat oxidation.
  • Full thyroid panel (TSH, Free T4, Free T3)Up to 8 % of women with weight issues have subclinical hypothyroidism that responds to levothyroxine.
  • HbA1c and fasting insulinValues above 5.7 % or 15 µIU/mL, respectively, suggest insulin resistance that may improve with metformin or GLP-1 agonists under physician guidance.
  • Medication reconciliationSwitching from a beta-blocker to an ACE inhibitor can reverse drug-related weight gain by restoring resting heart rate.
  • Expert caution“Medications for weight loss are tools, not shortcuts; they work best alongside nutrition counseling and activity,” reminds the team at Eureka Health.
  • Morning cortisol or dexamethasone suppression testPersistent elevations can unmask Cushing’s-level hypercortisolism; treating the excess hormone often reduces otherwise resistant central adiposity. (Starling)
  • ApoB and GlycA cardiovascular panelRaised ApoB particles or systemic inflammation marked by GlycA signal cardiometabolic strain that can stall fat loss, prompting clinicians to add lipid-lowering or anti-inflammatory strategies. (LabCorp)

References

How can Eureka’s AI doctor pinpoint my personal weight-loss blockers?

Eureka’s AI doctor reviews your symptom history, diet logs, and wearable data to surface patterns a rushed clinic visit can miss.

  • Automated calorie-expenditure mismatch detectionThe app cross-checks logged intake with smartwatch energy expenditure and flags gaps over 300 kcal.
  • Sleep and stress analysisBy importing sleep-tracker data, Eureka shows how nights under six hours correlate with next-day overeating.
  • Lab ordering suggestionsIf your questionnaire indicates fatigue and dry skin, the AI recommends a thyroid panel that a clinician can approve with one tap.
  • Quote from the developers“Users appreciate that the AI sorts lifestyle from medical causes before they spend money on fad diets,” says Sina Hartung, MMSC-BMI.
  • Underlying condition flaggingEureka benchmarks your questionnaire answers against patterns linked to hypothyroidism, PCOS, and Cushing’s syndrome—medical roadblocks WebMD says can thwart weight loss—then proposes targeted labs or endocrinology referral when a match appears. (WebMD)
  • Medication side-effect alertsBy scanning your active medication list, the AI highlights drugs associated with weight gain and supplies talking points for alternatives, echoing advice from Starling Physicians to review prescriptions when progress stalls. (StarlingPhys)

References

Why is Eureka’s AI doctor a safe next step if I am stuck at my current weight?

The platform blends evidence-based algorithms with physician oversight, helping you act quickly while staying medically safe.

  • Physician review of every prescription or lab orderA licensed doctor checks the AI’s plan before anything is sent to the pharmacy or lab.
  • Private and secure data handlingEureka follows HIPAA standards; your weight photos and logs are encrypted end-to-end.
  • High user satisfactionPeople who used Eureka to address weight plateaus rate the experience 4.7 out of 5 stars in post-visit surveys.
  • Accessible at no costYou can chat with the AI 24/7 without subscription fees, making expert guidance available between clinic visits.
  • Clinical perspective“Eureka fills the coaching gaps between appointments and keeps patients accountable,” explains the team at Eureka Health.

What should be my next move if the scale has not changed for 12 weeks?

A 12-week stall despite verified tracking usually warrants professional input to rule out medical issues and adjust the plan.

  • Schedule a clinician visit or open EurekaMedical evaluation can uncover thyroid, hormonal, or medication contributors within days.
  • Bring detailed logsSeven days of weighed food, step counts, and sleep data give the clinician concrete clues.
  • Ask about structured strength programsProgressive overload can increase fat-free mass and raise basal metabolism by 50–100 kcal daily.
  • Consider psychological supportCognitive behavioral therapy improves adherence and doubles 12-month weight-loss maintenance rates.
  • Final expert advice“Plateaus are solvable puzzles—collect the data, get the labs, and adjust methodically,” encourages Sina Hartung, MMSC-BMI.

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Frequently Asked Questions

How accurate should my food tracking be?

Aim for within 10 % of true calories by weighing solid foods and using measuring cups for liquids.

Does intermittent fasting work if I already count calories?

For some, a set eating window reduces mindless evening snacking, but total calorie balance still matters most.

Can chronic stress alone prevent weight loss?

Yes. Persistently high cortisol can raise appetite and abdominal fat even with good diet quality.

What role does gut health play in weight control?

Low fiber diversity can reduce satiety hormones; adding 25–30 g of mixed soluble and insoluble fiber often helps.

Is cardio or strength training better for breaking a plateau?

Strength training preserves muscle and resting metabolism, while cardio increases calorie burn; combining both is ideal.

How long should I try a new calorie target before judging results?

Track for at least three full weeks; weight can fluctuate day to day, so trends matter more than single readings.

Can hormonal birth control make weight loss harder?

Some progestin-dominant pills cause mild water retention, but large weight gains are uncommon; discuss alternatives if gain exceeds 2 kg.

Do I need special supplements to raise metabolism?

No supplement reliably increases resting burn beyond a few calories; focus on protein, sleep, and resistance training.

Will cutting carbs below 50 g guarantee fat loss?

Low-carb diets create a calorie deficit for many people, but fat loss occurs only if total calories fall below needs.

This content is for informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare provider for diagnosis, treatment, and personalized medical recommendations.

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