Two related questions from different readers:
So processed foods with carbs like rice and pasta and bread are problematic. What about potatoes? They’re vegetables. Do potatoes have fiber?
– Puzzled in Plaistow
In your book you talk about “processed food” a lot, highlighting that processes which remove fiber or add sugar are particularly harmful. Unless we start eating only raw vegetables, isn’t almost everything we eat processed? Isn’t cooking a process? Boiled or roast carrots are sweeter than raw ones… and fried (caramelised?) onions are sweet while raw ones aren’t. Does cooking reduce fiber or chemically increase the fructose content in food?
– Unsure in Upney
These are good questions. The processed vs. unprocessed distinction is generally a good one, but it is oversimplified and indirect.
What really matters, of course, is what is actually in your food at the end. Whether it got there naturally or artificially is, in itself, irrelevant.
Eating foods that are naturally high in sugar and/or have a low fiber-to-easily-digestible-starch ratio (reflected in a high glycemic load) is not a good idea. But there really aren’t that many such foods.
Potatoes do sort of fall into that category. They have a lot of starch and not that much fiber. The fiber-to-starch ratio is about 10 to 1. That isn’t very good.
Green vegetables like broccoli, on the other hand, have very little starch and quite a lot of fiber, relatively. The fiber-to-starch ratio in green vegetables is closer to 1:1.
There are also some fruits that are naturally high in sugar. Mangoes, for instance, are 14% sugar. That’s probably high enough to warrant eating mangoes only in moderation (as opposed to many other fruits which can be eaten with impunity). But 14% is nothing compared to processed foods like candy or kid’s breakfast cereals, which are often 40% sugar or higher.
So while there are some exceptions, the processed vs. unprocessed distinction is actually a pretty good one. It is possible to dream up a restricted diet of unprocessed foods that wouldn’t be very healthy (e.g. the potato and mango diet). But most unprocessed foods are healthy, so if your diet is a mix of unprocessed foods, you’ll be fine.
And don’t worry about the cooked vs. raw distinction. There may indeed be some benefits to eating some foods raw rather than cooked. So if you like your foods raw, then go for it.
But if cooking helps you to enjoy unprocessed foods more, so that you stick to eating them rather than reverting to eating processed foods, then you should definitely cook.
In summary: don’t overthink it. The important thing is to avoid processed foods and eat a mix of unprocessed foods. Everything else is relatively minor.