There are lots of things happening in your body and mind when you try to loose weight.
During the first week you may find it easy to loose weight by simply switching to a healthier diet. As your metabolism adjusts you wont be burning as many calories you used to burn. So losing additional weight will become harder making matters worse as the fat melts away you will start to experience increase in appetite.
After a meal fat cells releases a hormone called leptin into blood stream. This surge in leptin level signals the brain that you are full and you should stop eating. But with less overall fat people who lose weight show a measurable dip in leptin.
Brain scans of obese patients who had lost 10% of their body weight revealed less leptin leads to increased activity in the regions of brain that controls our desire to eat. The end result is not an increased appetite but an even stronger urge to eat fatty , high calorie food. Because your brain is trying to restore the body's leptin levels to normal.
How ever fighting that early impulse to gorge on pizza and donuts is worth it in the long run. Besides the decreased risk of heart disease , hypertension , high cholesterol and type 2 diabetes. Scientists studying overweight people discovered that losing just one pound of weight reduces four pounds of pressure on knees.
Losing excess weight also reduces strain on the blood vessels, increases the blood flow to brain and boosts overall brain function. Several studies have shown that people who under went weight loss surgery saw an improvement in memory concentration and problem solving skills in as soon as 3 months. Plus brain scans indicates that people who lose weight and kept it off for 9 months reacted differently when shown images of high calorie foods than before they lost weight. The brain regions that process reward, motivation and taste didn't react as strongly where as the areas that promote overall self control had a boost in activity.
So fighting those cravings early on might make them easier to control later. Turns out like anything else losing weight can get easier with practice.