sugar, besides its sweet taste and those quickly absorbed calories which are stored as fat, sugar starts an insulin reaction after spiking blood sugar levels. This is just a brief note, imagine the rest.
Which takes us to the second food to avoid, and they are, believe it or not, healthy foods that claim to be healthy and good for you. These 'healthy' food producers may reduce the fat in these foods, however they make up for it by increasing sugar and salt to create more flavor.
Salt, may provide some taste to your cooking, but avoid using a lot of it as it can lead to high blood pressure. Canned foods are high in sodium. There are many packaged processed foods that have high levels of sodium, one good example, potato chips.
Try to make your own homemade version of the foods you like. Including potato chips, with reduced amounts of salt, or exclude it altogether and replace it with healthy herbs and spices which would give it a salty taste, but without the salt.