I just followed this advice, lost 80lbs and feel much better: The more natural, raw and un-refined a food is, the healthier it is for you. And the more variety, the better.
Additionally, if you eat all natural unprocessed foods I don't think it's possible to get obese. Foods in nature simply don't have the calorie density of processed foods.
Red meats are probably the most ‘dense’ foods that exist in nature and the fattiest ones are 2-3 calories/gram. Lean red meat is 1-2 and white meat can be less than 1. Fruits, potatoes and veggies are all around 0-0.5.
Processed sweets, condiments and fried foods can easily exceed 5-6 cals/gram. People were never meant to eat food this dense in virtually unlimited amounts.
Coffee can be natural and unprocessed(just roasted) so it should be good.
Ever read “The Maker’s Diet” by Jordan Rubin? That is the hardest one to follow that I’ve seen.