This is not true at all. Most forms of food preparation destroy some portion of the raw nutrient value, although for some foods the nutrient value is indigestible to humans in the raw form so even eating it raw would not be a great option. If it destroyed all nutrient value then processed foods would have no energy content, and you would starve to death eating them. This is patently false to the point that it does not need any further explanation.
This includes all forms of cooking–tests show that steaming preserves nutrient value the best I believe of all types of cooking. I believe “direct flame” grilling destroys the most of the raw value. But you’re always going to end up with some remaining nutrients unless you literally char the food into ash, which is not really of any nutritional value, being you know, ash.
What are you referring to as processed? Study shows frozen and canned fruits & veggies (processed) just as nutritional as fresh, sometimes more, unless you’re able to consume right after picking. Cite
Processed meats however, ham, bacon, sausage, hot dogs and deli meats have harmful nitrates in them, and loads of salt.
And believe it or not there is indeed nutritional content in a Big Mac, although there are better ways to get it.
So. you’re suggesting that eating prepared foods every meal is fine, perfectly healthy? Read the OP again, this is about someone who is overweight and trying to lose such weight. You’re saying go ahead and eat prepared foods every meal, that’s not her problem.
“Rule of thumb” is not the same as "“hard cold fact”. Prepared foods as those that are ready to eat in 1 minute 14 seconds.