In beta oxidation of palmitic acid if final product is acetoacetate then net gain of ATP is:

Palmitic acid (16 carbons) For Palmitic acid complete oxidation, we require 7 beta oxidation cycles and 8 rounds of kreb cycle from 8 acetyl CoAs 1 beta oxidation cycle produce 4 ATP One kreb cycle from 1 Acetyl CoA produce 10 ATP after ETC. So Total ATP from complete oxidation of Palmitic Acid under normal conditions 7 x4 = 28 (beta oxidation) 8x10=80 (kreb cycle + ETC) Total 108 ATP 2 ATP require for fatty acid activation Net ATP =108-2 = 106 But the question asks about if all acetyl-CoA produced from beta oxidation is conveed to acetoacetate instead of undergoing TCA cycle then what will be ATP yield? If the final product is acetoacetate, then it will not be used in kreb cycle so 80 ATP from Kreb cycle will not be formed. Instead the acetaoacetate will form ketone bodies. Hence only beta oxidation ATP will produce 28 ATPs from 7 cycles. So net ATP will be = 28 - 2 = 26 ATP (2 ATP required for activation of fatty acid)