I used to tell clients the standard issue line that when it comes to weight loss, it doesn't actually matter WHAT you eat, it's how MUCH. We've been told this over and over right? It all comes down to calories in, calories out, right? If you're overweight, it's just that you need to eat less and exercise more right? Well maybe, and maybe not. I've worked with many clients over the years who have counted calories religiously, cut portions, deprived themselves, and done legitimately hard workouts consistently and lost negligible amounts of weight if any. So what gives? The science says they should be losing weight, but they're not.
When one digs a little further into the topic, it's not that cut and dried. There are other powerful over-riding influences such as the hormone insulin that turn the energy balance issue upside down. According to Gary Taubes, author of Why We Get Fat And What To Do About It,
"...science itself makes clear that hormones, enzymes, and growth factors regulate our fat tissue, just as they do everything else in the human body, and we do not get fat because we overeat; we get fat because the carbohydrates in our diet make us fat. The science tells us that obesity is ultimately the result of a hormonal imbalance, not a calorie one-specifically the stimulation of insulin secretion caused by eating easily digestible carbohydrate rich foods, refined carbohydrates, including flour and cereal grains, starchy vegetables such as potatoes and sugars, like sucrose (table sugar) and high-fructose corn syrup. These carbohydrates literally make us fat, and by driving us to accumulate fat, they make us hungrier and they make us sedentary."
So to make this short and to the point, if you want to lose fat cut the carbs. Especially the refined ones. You should be avoiding cereal grains, flour, potatoes, and limiting certain high glycemic fruits. Unless you have a moral issue with eating meat, and you're a vegan, you should be eating meat, vegetables, nuts and seeds, berries, and using certain oils, such as olive oil and coconut oil. Severe calorie restriction is rarely if ever a good idea. Calories are not irrelevant, but when you get your food quality under control, you will generally find that the energy balance issue will take care of itself. Your natural signals of satiety will be restored and you won't have the roller coaster blood sugar. Just get rid of the empty nutritionless carbs, the pasta, rice, grain, bread, oats, tortillas, donuts, chips, etc...etc...you get the idea. It takes a few weeks to get acclimated and then you're good to go!