No, it's not as simple as that. If your digestion is messed up, if your energy production is messed up, you can eat food all day long and still be in a functional energy deficit if the cells are not getting the CO2 they need. That's the problem with hypothyroidism/diabetes/etc.
no exercise puts the organism in a downward spiral, as he focuses more on his own digestion, becomes too self aware, is miserable all the time, and slowly deteriorates. Going out and being active puts the organism in an upward spiral, as he becomes happier, lymphatic system starts moving, heart rate increases temporarily, stops focusing on digestion, can all of a sudden digest foods it couldn’t before because it’s not stressed. Natural drive for more dietary energy. comes back so eating becomes more natural. and food ceases to be the main aspect of life which is not a natural thing for it to be for humans. Sitting at home and evaluating oneself after every meal will never bring good health.