Most diets are set up to be a short term goal not a lifestyle change. One of the reasons is because no one can maintain the restrictive pace long term. Notice how these diets are designed for you to lose weight for a particular goal like a wedding or a reunion. What happens after that? You’ve heard it a million times. Weight comes back with interest. Why is that?
The question you should really ask is, “Am I losing weight or am I losing fat?” This makes all the difference in the world. We’ve all seen that person who lost a ton of weight and now looks sickly thin and you wish he would put some weight back on. When following most of these fad diets out there, what you are losing is muscle along with water and maybe some fat. 
Let me point out to the fact that losing muscle is extremely detrimental and counter productive to the weight loss goal. Look for meal plans that are designed to protect from muscle loss by making sure you consume the appropriate amount of protein. Remember, the more lean muscle you have, the more calories you burn. When you lose muscle as a result of these fad diets, you are left worse off when you go off these diets. Now you have less muscle and if you go back to eating the way you were eating before, you will gain weight. That’s why all these diets fail.
Fat burning is what you need to focus on when looking to trim down. For example, cutting down on foods like sugary treats, breads and pastas is one way to prevent your insulin levels from spiking which causes fat storage. Another would be doing cardio workouts a few times a week that last longer than 30 minutes preferably outside. Flooding your cells with oxygen torches fat storage and uses it for fuel.
In summary, when trimming down is your goal, try not to concentrate on the number of pounds lost but on the percentage of fat lost. Get your fat percentage measured and track your fat loss not your weight loss. You may weigh the same but have lower fat percentage which will result in you looking more fit. Meal plans that are designed for muscle preservation and fat loss will leave you with a healthier and physically fit body. But even more importantly, with more muscle and less fat, you will be able to sustain this for a lifetime.