&gt; It&#x27;s disconcerting in the same way that liposuction is disconcerting. You could make very similar arguments about liposuction as you did about gut engineering: if it improves health, then it&#x27;s a good thing.<p>Liposuction is generally cosmetic; I&#x27;m not aware of it ever being indicated for health reasons. (Though, given that, while <i>most</i> body fat changes <i>do not</i> involve changes in the number of fat cells, just growing or shrinking existing cells, extreme adult weight gain <i>does</i> result in gaining additional fat cells which don&#x27;t go away with weight loss, its at least plausible that there might be <i>some</i> situations where it would be the best approximation to achieving the state the body would have had without the intervening extreme weight gain.)<p>&gt; But at the end of the day, it doesn&#x27;t address the issue of being able to control what you do with your body in the interest of your health.<p>If overweight people have more efficient gut microbiomes, the problem they have compared to normal-weight people isn&#x27;t a self-control problem, its a gut biome problem. Insisting that it must be addressed as a self-control problem (dubious whatever the source of the problem is, if that&#x27;s not the most efficient intervention) seems downright perverse.