If you are looking to improve your exercise capacity you may wish to consider a Keto diet, at least in the short term.
Study: An 8 week Ketoginic low carb, high fat diet enhances exhaustive exercise capacity in mice (Published in Nutrients, May 2018). The benefits the researchers state is from the bodies ability to improve the utilisation of fat, which is the largest pool of energy within the body. The 8 week keto dieters also dropped weight dramatically, which is a good route to improving power to weight ratio. This loss of weight was even after the participants on the Keto diet consumed more calories. An additional benefit was that even though the keto diet participants showed improved running time, there was no increase in aggravated muscle injury.
If you would like to read the article, follow the link: https://www.mdpi.com/2072-6643/10/6/673/htm