High protein is key

This study shows eating
700 calories over maintenance
no fat gain body comp


conclusion
In conclusion, it is evident that overfeeding on carbohydrate and/or fat results in body composition alterations that are different than overfeeding on protein. It is commonly believed that 3,500 kcal is equivalent to 0.45 kg (1 pound) of fat and that changing energy balance in accordance with this will produce predictable changes in body weight. However, the overfeeding literature to date does not support this assertion. Dietary protein appears to have a protective effect against fat gain during times of energy surplus, especially when combined with resistance training. Therefore, the evidence suggests that dietary protein may be the key macronutrient in terms of promoting positive changes in body composition.


Study link
https://www.ncbi.nlm.nih.gov/pmc/art.../#!po=0.694444