Most restaurants smuggle obscene amounts of butter and sugar into dishes to make them more delicious so you'll come back. It's not unreasonable to assume that every subcomponent of a recipe might have sugar added individually.
In packaged foods, there is a whole science of masking the sugar and fat content to make it more addictive without triggering your inbuilt satiety mechanisms [1]. This is what today's engagement optimisers did for money in the 50/60s.
You could argue that these "innovations" were precisely to subvert the intuition that visual appearance of food (and other natural sensors) can be relied on to assess their nutritional properties.
> Most restaurants smuggle obscene amounts of butter
God I wish that was true. Butter is far too expensive to do that, so restaurants will use the cheapest alternative (usually soybean oil with butter flavoring) instead.
There is absolutely, unequivocally, 0 chance this can be accurate within any kind of reasonable bounds. I'm guessing you haven't done much calorie tracking if you think this could possibly be true.
I can make two dishes that look identical and have +/- 50% caloric content, easily.
> I expect a strong correlation between the visual appearance of food and its caloric content
This doesn't pass even simple scrutiny. There are so many caloric ingredients that aren't visible in food. You can't tell just by looking whether a rice dish contains half a stick of butter.
This is completely wrong. For example, you can increase the amount of oil or butter in a recipe, doubling or tripling its calorie count, and you would never be able to tell from a picture.
The point of the app is to figure out the calories of a meal automatically by taking a photo.
Without knowing the amount of sugar, butter, oil, etc. is used in a dish, one cannot know if a dish is worth 250 kilocalories or 750 kilocalories.
If I need to manually fill in details of ingredients and amounts to get to the calories to be have an error margin of less than 100%, then the app is not useful and is at best misleading.
That’s not true. They have the same amount of calories roughly. It’s physically impossible for animal fat to have that many calories. Tallow has 900 calories per 100 grams while olive oil has 884. They are almost pure fat and pure fat has 9 calories per gram.