Animals are often not growing at the maximum rate, but can compensate for a bad start of life by further increasing growth rate. While this compensatory growth is widespread, its direct fitness consequences are seldom investigated and its genetic basis is unknown. We investigated the genetic regulation, as well as fitness and lifespan consequences of compensatory growth in response to temperature, using C. elegans knockout of the thermo-sensitive TRP ion channel TRPA-1, involved in temperature recognition. We exposed juvenile worms to cold, normal or warm temperatures in order to delay or speed up development. After returning to normal temperature, we found that wild-type worms where early development was delayed, expressed compensatory growth and catched up in size, while juvenile exposure to warm temperatures expressed slowed-down growth and small size. Compensatory growth also altered the reproductive schedule towards early reproduction, so that rate-sensitive individual fitness increased even though total reproduction was unaffected. Surprisingly, no lifespan cost of compensatory growth was found. In contrast, juvenile temperature did not induce compensatory or slowed-down growth in the trpa-1 knockout mutants, and consequently did not affect fitness. We show that temperature-induced compensatory growth in C. elegans is regulated by the trpa-1 and can increase fitness.