Those gels are overrated. 'Re-fueling' is not as necessary as they want people to believe. The gels are well-marketed, aimed towards the mass market of ordinary amateur into sport or fitness. For whom the product is mostly unnecessary. But, no, if you are exercising or taking part in a sport for 30 minutes to 1 hour, there's absolutely no need to re-fuel. The human body is quite capable of storing enough reserves. Of course, they are beneficial to super-triathlons, and tennis matches that can go 4,5,6 hours, long distance cycling, endurance ultra-distance running etc. etc.