keep healthy fats, olive oil, nuts and animals.
if you really want to get into it you need to look at the research as it goes totally against conventional claims and government recommendations.
avoid fast acting carbs.
and it's a total myth that a calorie is a calorie and it doesn't matter what you eat,
I want go in depth, but i'll give you some examples of research that has been done.
one study that compared Conventional low fat diet vs mediterranean (olive oil based) and mediterranean (nuts based) had to be stopped early on ethical grounds ,as the reduction in cardiovascular dieses markers was so great it was unethical for the people on the low fat diet to continue to, due to the massive increase in health risk for that group.
two groups of rats one fed high carb low fat and the other high fat, both fed only enough to maintain body weight.
not only did they have to reduce the calories for the low fat rats compared to the high fat ones, at the end of the study, the low fat rats had significantly more fat and less muscle mass. (yes its rats even the researchers acknowledge theres a difference, however try getting the funding and the volunteers, especially as iirc it was 15 rat year equivalent, this is a major issue at the moment, lack of money to do full scale clinical trials)
when volunteers where put under a MRI after eating (I believe it was a cinnamon bun) the reward centre lit up like a light house, in same way as addictive drugs and that was for every single participant. if you are trying to be healthy or lose weight then probably not a good idea to have such things in moderation.
one of the better research into diet compared, conventional low fat, (60% from carbs) Mediterranean (40% calories from carbs) and atkins style (10% calories from carbs) very low carb diets, each participant was given the main meal so that at least that meal was the same. after analysis they found that just from the diet the high fat low carb burnt an extra ~350 calories a day, and mediterranean 150 calories compared to the low fat high carb diet.
the diet most often sited as proof for high carb low fat working, well was biased from the start, the only group to receive counselling was the high carb low fat group, who received 18 individual sessions in the first year and then group sessions in the following 6 months.
still only managed 5lbs more weight loss in the first 12 months and no difference by 18 months.
another study comparing a fast acting carbohydrate breakfast vs a slow acting carbohydrate breakfast. group who had fast acting, had a 33% reduction in memory and cognitive reasoning.
the research that saturated fat causes CVD used cherry picked numbers and was very unscientific. but it stuck.
and that's before we look at insulin resistance, hunger, cravings etc. which are all very much affected by the types of food we eat.
basically a massive social experiment which has failed, caused by lobbying and biased research.
it's taking so long to change as there is little money in diet research and its hard to force people to follow a set parameter for a year or two under clinical standards. this leads to a lot of conflicting research as they are relying on volunteers to be truthful about what they have eaten, which as they found out is well less than accurate.