"What I ate" is a reminder app which will assist you in your efforts to not overeat (and eat the right things). You take a photo of every meal you have with "What I ate" and it shows you the photos of the previous meals you had on that day. Now you can instantly tell whether you should eat something or better put it back in the fridge. Or you can see that you didnt have enough vegetables or fruits yet and eat one of those.
You can picture "What I ate" as part diary and part conscience - it will help you remember what you ate and thereby help defeat your inner weaker self. It will also help you stick to your dietary plan, but it wont patronize you.
The problem with this kind of apps is that they often are too complicated and take too much time to use. "What I ate" takes the minimalistic approach and comes without distracting features and lets you focus on your main goal: tracking your diet. You wont be hassled to count calories. You wont have to include information about where or with whom you had a specific meal.
The only thing you *have* to do is take a photo of your meal. "What I ate" will show you what you already ate today - thats it. It can only assist you, it cant do the heavy lifting for you.