Just from my anectodal experience, low carb diets seem to be easier to follow for people who like meat: fats and proteins are something that many people from older generations consider "real" good food. Also eating lots of carbs is sp much easier than eating lots of proteins and fats, that it's simple to reduce your caloric intake by reducing carbs.

if your dad enjoys numbers, wifi scales like Fitbit Aria can make it much effortless to track weight and not be de-motivated by natural daily variations in your weight.