"Once I've added some nice, beautiful, healthy whole foods into my diet, which foods should I squish out first?". This is a good question, so here are my recommendations:
Gaining weight and losing weight has nothing to do with grams of fat or the amount of calories you eat in a day. But it does have everything to do with blood sugar and insulin.
When we eat food the carbohydrates are broken down and are converted into glucose, which our body uses as energy. When the glucose in our blood rises, our pancreas secretes insulin and this allows the glucose to enter our cells to be used as energy.
Our liver is constantly watching this process to make sure that we have just the right amount of glucose and insulin in our blood. It watches hormones in particular, so it's insulin that tells the liver if your blood sugar level is too low or too high.
If our blood sugar is higher then we need for energy, the insulin in our blood signals our liver and our liver stores this excess energy as fat. The liver converts the glucose into triglycerides and then are sent through our blood stream to our fat stores.
Fat, on the other hand, can be used as energy, but this is only when necessary. Fat is used in MANY important processes in our body, and it's only as an almost last resort does our body use it as energy (it uses protein as a very last resort). Our liver has to convert the fat into a glucose molecule and will only do so as needed, so our blood sugar doesn't spike with fat. Otherwise, the fat is used to make cell membranes, hormones, etc. Fat is a VERY important molecule in the body.
Fat and protein affect how carbohydrates enter into your bloodstream. A higher fat or protein meal actually slows down the break down of the carbs, creating a slower burning carb and that keeps your blood sugar steady. The more refined the carb is, the faster it enters your bloodstream.
When we eat a high carb meal, or a refined carb, our blood sugar spikes - this is when our liver stores fat. We can tell that our blood sugar spiked by looking at when our blood sugar crashes - this is seen as any emotion around hunger. Irritability, tiredness, lack of patience, etc are all signs that earlier your blood sugar spiked and now you're crashing. Look back at your last meal and see why it caused a crash. Leveling out your blood sugar so you're no longer on the blood sugar rollercoaster is how to stop gaining weight, and how to lose weight.
We need to stop blaming fat and eat healthy whole foods to maintain a healthy body and a healthy weight!