The big problem with eating doughnuts and ice cream is not just that they're short on nutrition. It's that fatty, sugary foods make it very hard not to overeat. There are specific fat/sugar ratios that supress our "full" signal and just make us crave more. Ice cream, cheesecakes and probably most doughnuts fall onto this category. In lab tests I believe they've fed the optimum ratio to rats and they just eat themselves to death.

I've found it hard to reduce my food intake any time I've tried to re-establish a trend of weight loss. It has sometimes taken me a few false starts over a few weeks or even months but once I get going it becomes easier. Just treat it like a habit change not a transient diet. Don't give up just because you don't see the weight disappear at first. It will work.

I actually think it's a lot easier to reduce intake if you eat better quality, less processed food and make it enjoyable but in smaller portions. Don't punish yourself but avoid low quality food.