fitness facts . Avoid mixing carbohydrates and proteins Most nutritionists are reserved about this combination. It slows the digestive process. Proteins are digested differently than carbohydrates. Mixing acidic foods like meat, fish and cheese with the alkaline fruit and vegetables would cause fermentation in the intestines. If you can’t give up on your steak and baked potato, no worries, you can still have them. Just not during the same meal.