losing body fat means that you must continuously make choices that decrease your comfort in some way - eating fewer highly rewarding foods, maintaining a state of hunger, increasing activity level
It is interesting to see "increasing activity level" as being a decrease in comfort. But I suppose that's because "comfort" here isn't defined absolutely. I also am not sure that "comfort" is an attribute that should be optimized for in disregard for all others.
If this statement is read as "anything that does not have 100% positive feedback is undesirable" then I think it would be very challenging to make any improvements in a person's life.
But then I also don't think that "comfort" is necessarily an ideal target to optimize. I think a more holistic measure such as "satisfaction" is a more productive target. We can find "satisfaction" in things that are not 100% pleasant but which in turn result in greater happiness or feelings of contentment than doing only those things that have positive feedback.
This measure of "comfortable" also does not seem to account for the secondary effects of "comfortable" choices. E.g., if we eat only "highly rewarding foods" and become obese we see discomfort in other parts of life (loss of mobility, health issues, difficulty performing mundane physical tasks, etc)