How many ATP molecules are produced from the breakdown of fatty acids?

• A. 60
• B. 90
• C. 106
• D. 120

Answer: (C)

Fatty acid energy comes mainly from beta-oxidation turning the fatty acid into acetyl-CoA, plus the acetyl‑CoA units feeding the citric acid cycle, with a small cost to activate the fatty acid first.

For a common long-chain saturated fatty acid like palmitate (16 carbons), beta-oxidation occurs in seven cycles. Each cycle gives one FADH2 and one NADH, which together contribute about 28 ATP (7 × [1.5 + 2.5]). The 16-carbon chain yields eight acetyl-CoA molecules; each acetyl-CoA entering the citric acid cycle produces about 10 ATP (3 NADH → 7.5 ATP, 1 FADH2 → 1.5 ATP, and 1 GTP → 1 ATP), totaling around 80 ATP for eight acetyl-CoA.

Add those: ~28 ATP from beta-oxidation plus ~80 ATP from the acetyl‑CoA oxidation equals ~108 ATP. Subtract 2 ATP used to activate the fatty acid to acyl-CoA, giving a net of about 106 ATP per palmitate.

So the breakdown of fatty acids yields roughly 106 ATP, which explains why this value is the best answer for the question.