I can’t remember all the facts about this, but there is something about the body adapting to starvation. Over the first week your insulin response would get more sensitive to carbohydrate intake there for you would use and store (fat) more of the food you eat.
But there is a lot of stuff that plays into this, try to measure out what you eat during a day. And when! for instance, if you skip breakfast, you are very much likely to put on weight.
If you are looking into weight loss you should eat many small meals.
How are your hormonal values? Thinking of thyriod glan and/or others that might be related to weight. Ask your MD.