@Glomoro Sure, you are using less energy during your sleep. Your total daily energy expenditure doesn't change based on whether you eat 0 hours before sleep or 5 hours before sleep however. So you will store fat anyways provided you are in a caloric surplus, or vice versa, you will lose fat if you are in a caloric deficit. Feeding time should be a non factor, or a very minor one.
This manga specifically appears to not have an official translation. So you'd likely still be reading it here, unless you read Japanese.