Loss of smell is a well-studied disorder long before COVID-19 ever came around: "However, some reports (Mattes et al., 1990; Mattes, 1993, 1995) are contrary t

Loss of smell is a well-studied disorder long before COVID-19 ever came around: "However, some reports (Mattes et al., 1990; Mattes, 1993, 1995) are contrary to the earlier suggestions that anosmics do not experience problems related to their food intake. These authors report that ~14% of anosmic patients experienced a body weight gain exceeding 10% while ~6.5% experienced a loss of at least that amount." (https://academic.oup.com/chemse/article/24/6/705/320339 https://academic.oup.com/chemse/article/24/6/705/320339) Some people might with diminished (but not completely eliminated) senses of smell might compensate by eating more of certain flavors that they CAN taste. Also worth noting that there are tons downsides, ignoring the obvious lack of sensory pleasure most people get from food. They are less likely to smell rotten and spoiled food, smell smoke from a nearby fire, etc.