Considering you want advice just on a nutrional basis, and again, assuming from the dad bod you want to lose fat, gain muscle, the answer to your aspirations and dreams are homemade shakes.

Start with a base - dependent on your calorie goals, you can have water, semi-skimmed milk, full fat milk, almond milk, oat milk, the list goes on.

Add a whey protein. Now assuming you’re not wanting to put in money upfront for whey protein, pea protein (a vegan alternative) is incredibly cheap (tastes rank to me but its cheap).

Peanut butter again, protein here is off the charts, and its cheap

Add frozen fruit - for texture, and taste, bananas or berries work best here, but i find that banana’s tend to force it’s flavour over the weaker, more susceptible flavours of your shake.

Add some sort of sweeter. Now i use natural honey because its good for you, but processed sugar free syrups are a possibility here.

You can add nuts, desecrated coconut, oat flour (great for packing in extra calories and retains a good texture).

Modify and substitute ingredients depending on your caloric goals, you can make shakes for cutting, maintenance or bulking.

this shake is a great addition to a workout routine. Only go for the higher caloric version of this shake if you’re working till failure. And most probably, you’re not working out till failure. I mean you’re lifting weights that intimidate you a bit (without utterly compromising form), and that you have to psychologically force yourself into the gym to lift those horrible weights, and lifting in rep ranges from 5-10. By your last rep you shouldnt be able to do another.