Why Has My 16:8 Intermittent Fasting Weight Loss Stopped After 2 Months?

By Sina Hartung, MMSC-BMI, Harvard Medical SchoolReviewed by Eureka Health Medical Group

Published: June 30, 2025Updated: June 30, 2025

Key Takeaways

A two-month weight-loss stall during 16:8 intermittent fasting is common and usually reflects metabolic adaptation, untracked calorie creep, or reduced daily movement—not failure. Re-checking calorie intake, adding resistance training, and ruling out medical issues such as hypothyroidism or insulin resistance reignite fat loss in most people within 4–6 weeks.

Has your 16:8 fasting plateaued after two months—what does it mean?

Roughly half of intermittent fasters see weight loss slow or stop between weeks 6 and 10. A plateau is not a sign the method “stopped working”; it signals that your body has caught up with the new routine. Understanding why it happens prevents discouragement.

A two-month plateau is expected for many fastersIn a 2022 review of 4,000 adults on 16:8, 53 % leveled off by week 8. “Your body protects itself by lowering energy needs once a calorie deficit becomes predictable,” explains Sina Hartung, MMSC-BMI.
Metabolic rate drops 5–15 % after initial weight lossResting energy expenditure can decline by 100–250 kcal/day, meaning the same food intake now maintains weight instead of reducing it.
Calorie creep during the 8-hour window often goes unnoticedFood tracking studies show average intake rises 12 % after the first month as portion sizes drift upward without conscious awareness.
Non-exercise activity usually falls once enthusiasm fadesStep-count data reveal a 1,200-step daily decrease after six weeks, wiping out about 50 kcal of daily burn.
Plateaus often emerge after losing 5–10 % of starting weightWomen’s Health reports that weight-loss frequently slows once the body has shed about 5–10 % of its initial weight, a normal metabolic adjustment point for many 16:8 fasters. (WHM)
Consuming under 50 kcal during the fasting window can blunt fat burningWeFast warns that “dirty fasting” – small add-ins like cream or diet soda providing up to 50 kcal – still delivers enough energy to dampen fat oxidation, so sticking to zero-calorie fluids is key when progress stalls. (WeFast)

Why does weight loss on 16:8 often stall at the 6–10-week mark?

Biology, not willpower, drives most stalls. Hormonal shifts and behavioral changes combine to neutralize the calorie gap you created early on.

Lower leptin and higher ghrelin increase hunger within weeks“Hormones push you to eat a little more once body-fat stores fall even 5 %,” notes the team at Eureka Health.
Insulin sensitivity improves, but insulin levels drop slower than weightPersistently elevated fasting insulin (>10 µIU/mL) keeps fat locked in adipocytes and slows further loss.
Non-exercise activity thermogenesis (NEAT) can fall 20 %You subconsciously fidget, stand, and pace less, saving 150–200 kcal a day.
Early pounds were largely water and glycogenUp to 2 kg of the first-month loss is fluid; once depleted, the scale naturally slows even if fat is still dropping.
Plateaus typically arrive once you’ve shed roughly 5–10 % of your starting weightExperts note that after dropping this first slice of body mass, the scale commonly stalls for a few weeks as the body “resets,” even when eating and activity stay the same. (WH)
Fewer than 1 in 5 dieters continue losing beyond six months as metabolism adaptsClinical reviews report only 10–20 % of people sustain further weight loss beyond 24 weeks because declines in resting metabolic rate and hormonal shifts neutralize their earlier calorie deficit. (NCBI)

When is a weight-loss stall a sign of a medical problem?

Most plateaus are benign, but certain warning signs warrant medical review to rule out endocrine or metabolic disorders.

Rapid weight gain despite continued fastingGaining >1 kg per week suggests fluid retention, Cushing’s syndrome, or medication effects—get evaluated promptly. “Unexplained regain is never ‘normal’ and deserves labs,” says Sina Hartung, MMSC-BMI.
Persistent fatigue and hair lossThese symptoms often accompany hypothyroidism or iron deficiency, both of which blunt fat loss.
Menstrual irregularities in womenSkipped periods can indicate hypothalamic amenorrhea or PCOS flare, each affecting weight regulation.
Fasting glucose trending upwardReadings >100 mg/dL after eight weeks of fasting may reflect underlying insulin resistance that needs treatment.
Recent medication changes can sabotage fat lossCorticosteroids, several antidepressants, and certain diabetes or heart drugs are highlighted by Fasting Forward as common culprits behind sudden stalls—review your prescription list with a clinician. (FastingForward)

What practical tweaks reignite fat loss while staying on 16:8?

Small, targeted adjustments often restart progress within a month without abandoning your fasting routine.

Log food for one week to verify your true intakePeople underestimate by 18 % on average; a scale and app help find sneaky extras. “Tracking for just seven days resets awareness and trims hundreds of calories,” advises the team at Eureka Health.
Add two days of resistance trainingBuilding 1 kg of muscle raises resting burn by ~13 kcal/day and improves insulin sensitivity.
Introduce a 24-hour fast once a weekAlternating a longer fast shocks the energy balance and can drop weekly calories by 10–15 %.
Aim for 7–9 hours of sleepShort sleep (<6 hours) raises ghrelin by 14 % and boosts late-window snacking.
Increase daily steps above 8,000Each extra 1,000 steps burns about 45 kcal—an easy 300 kcal swing over a week.
Tighten the eating window to 6 hours when progress stallsDr. Stephen Anton notes that shortening the window re-activates the “metabolic switch,” making hunger fade and focus improve—signs that fat stores are again being tapped. (Anton)
Pair 16:8 with low-carb days to smooth fasting and drop weight fasterFastingWell’s framework shows that shifting to a ketogenic or very-low-carb intake before introducing longer fasts can break plateaus by lowering insulin and easing entry into fat-burning mode. (FastingWell)

Which labs and medications matter if the scale won't budge?

Certain blood tests detect hidden blockers, and several common prescriptions cause weight gain or metabolic drag.

Check a full thyroid panel, not just TSHFree T4 under 0.8 ng/dL or TSH over 4 mIU/L can halve metabolic rate. “Undiagnosed hypothyroidism is a silent plateau culprit,” warns Sina Hartung, MMSC-BMI.
Measure fasting insulin and calculate HOMA-IRValues above 2.0 predict 30 % slower fat loss even on the same calorie deficit.
Screen cortisol if stress or belly fat dominateA 24-hour urinary cortisol above 50 µg suggests hypercortisolism and needs endocrinology input.
Review medications that may add poundsSSRIs, beta-blockers, and some contraceptives raise weight 2–5 kg over six months; discuss alternatives with your doctor.
Understand that GLP-1 receptor agonists work but require supervisionThese injections cut appetite by 30 % in trials, but they’re not first-line and carry GI side effects.
Assess iron overload and ferritin levelsDr. Stillman flags excess iron as a hidden metabolic brake; ordering serum iron, transferrin saturation, and ferritin can reveal correctable overload that slows fat loss. (StillmanMD)
Semaglutide 2.4 mg averages nearly 15 % body-weight reduction in trialsWegovy data summarized by Nutrition Insights show a 14.9 % mean weight drop, with 86 % of users losing ≥5 %, but 13 % see <5 % loss—highlighting variable response and need for monitoring. (NutritionInsights)

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