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The VerdictHIGH CONVICTIONVerdict Score 81Worth-It: Poor ROI (25/100)

Your body burns fat using stress hormones in your blood — not from the muscle working next to it.

Stop doing ab exercises to lose belly fat. Tonight, replace any isolation work you've been doing for fat loss (crunches, leg lifts, side bends) with compound movements — squats, rows, walks. This is the evidence-based fix. The targeting was never working.

  1. The largest study ever done on this — 1,158 people across 13 trials — found that targeted exercises had essentially zero effect on fat in the area being worked.
  2. The "burn" you feel during crunches is real, but what's being used is fuel stored inside the muscle fibers, not the fat layer sitting above them.
  3. You can't choose where fat comes off — but a caloric deficit is the only thing that makes any of it come off.

Think of your fat stores like money spread across multiple bank accounts. When you exercise, your body makes a withdrawal announcement to all accounts at once — through hormones in your bloodstream. It doesn't matter which account is closest to the branch where you made the deposit. The hormones travel everywhere, and your genetics decide which account gets drawn down first.

SH
Dr. Seth Holbrook, DPT — Doctor of Physical Therapy • Coach to 300+ clients
I built The Verdict to cut through recycled health advice and show what the evidence actually supports.

The Verdict — Research Review

Spot Reduction —
Truly Impossible?

The science of why crunches can't burn belly fat

WRONG
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Stop doing ab exercises to lose belly fat — replace them with compound movements tonight.

Swap any isolation work you've been doing for fat loss (crunches, leg lifts, side bends) with squats, rows, or a brisk walk. The calories burned from compound work create the systemic deficit that actually shifts fat.

No equipment needed. Can be done tonight.

The Verdict

Your body burns fat using stress hormones in your blood — not from the muscle working next to it.

Think of your fat stores like money spread across multiple bank accounts. When you exercise, your body makes a withdrawal announcement to all accounts at once — through hormones in your bloodstream. It doesn't matter which account is closest to where you made the deposit. Those hormones travel everywhere, and your genetics decide which account gets drawn down first.

  1. The largest study ever done on this — 1,158 people across 13 trials — found that targeted exercises had essentially zero effect on fat in the area being worked.
  2. The "burn" you feel during crunches is real, but what's being used is fuel stored inside the muscle fibers themselves, not the fat layer sitting just above them.
  3. You can't choose where fat comes off — but a caloric deficit is the only thing that makes any of it come off at all.

Want the full evidence? Keep scrolling

Practical application for fat loss

The Practical Takeaway

What to Actually Do

Conviction

HIGH CONVICTION

Supported by the dominant mechanistic model of fat mobilisation, large-scale meta-analytic data (N=1,158, ES=−0.03), and specific debunking of the methodological artefact in the only plausible outlier study. The catecholamine model of lipolysis is one of the most robust mechanisms in exercise physiology.

What Would Change This

A 16-week within-subject RCT (N≥150), metabolic ward-controlled, using MRI to unequivocally separate subcutaneous fat from intramuscular fuel stores — showing >5% greater subcutaneous fat reduction in the trained vs. untrained limb. No such study currently exists. DEXA-based findings are insufficient given the measurement confound.

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Sources

Verdict Score

How strong is the evidence for the claims in this review? Higher = more confidence the claims are supported. This does not measure how large the effect is or how important it is compared with other levers.

81 Strong evidence
80–100Strong evidence ◀
60–79Mixed but supportive
40–59Uncertain
0–39Weak support

Action ROI

Is this worth your time, money, effort, risk, and trust for this goal? Different from Verdict Score (evidence strength) and Leverage Map (relative importance) — Action ROI is the worth-it call once friction is priced in.

Action ROI score
25/100 Poor ROI Trust grade B
No. Targeted exercises do not remove fat from the area you train. Fat loss is driven by systemic catecholamine release across all depots, not by which muscle is contracting. Train the muscle for strength or shape if you want, but the fat-loss lever is a caloric deficit, not exercise selection.
Time
High
Money
Medium
Effort
High
Risk
Low
Why this score
Why it didn’t score higher
Best for
Lower ROI if
Minimum effective dose
Not applicable. The intervention is unsupported. The minimum action is to redirect time and money toward the actual fat-loss levers: a sustained energy deficit, compound full-body lifts (squat, deadlift, row, press), daily walking and step volume, and adequate protein. Train a muscle for strength or shape if you want, but do not expect targeted exercise to determine where fat comes off.
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