While I have no intention of ever going back to eating meat, after two years and a half of eating vegan food I have reintroduced in my food an ingredient of ani

While I have no intention of ever going back to eating meat, after two years and a half of eating vegan food I have reintroduced in my food an ingredient of animal origin, which is whey protein concentrate. It is likely that this exception will be temporary, because there already exists the technology of producing whey protein by a culture of a genetically-modified fungus. There are good chances that in at most a decade such protein production by fungal cultures could substitute the whey protein and the egg-white protein of animal origins. In any case for now I did this step back because with an 100% vegan diet it is extremely difficult to satisfy simultaneously 4 conditions: a high enough daily protein intake, but without a too high energy intake that would cause a weight gain, and without paying more for the vegan food than for a meat-based food, while having a sedentary life style. If any of these 4 constraints is relaxed, then it becomes easy to eat a vegan diet. When you are willing to spend much more money for vegan food than for meat-based food, then there are a lot of plant protein extracts that are many times more expensive than chicken meat. When you are doing a hard physical work that requires eating more than 3000 kcal per day, then it is easy to combine proteins from cereals with proteins from legumes, so that you will eat enough proteins per day. On the other hand, if you must satisfy all 4 constraints, that is difficult. In Europe where I live, there exists only one way to satisfy all 4 constraints, by extracting at home gluten from wheat flour, which requires time and water. The rest of the proteins can be obtained from legumes such as lentils, peas, chickpeas or beans. Even by dumping most of the starch from wheat flour, after eating enough gluten and legumes you can eat only small quantities of other food without exceeding the admissible amount of calories per day. This makes the daily menus too monotonous. So after two years and a half, I have begun to use whey protein concentrate (from which I make a cheese substitute by mixing it with vegetable oil and other ingredients in smaller amounts; this has the aspect and taste of melted cheese, but it has a much healthier fat content; where I live whey protein concentrate is a little cheaper than chicken meat). This allows to add proteins to the menu whenever needed, with only a minimal addition of calories, which allows a much greater freedom in the choices of food. As long as I have been eating strictly vegan food I had to completely avoid any starchy vegetables, e.g. potatoes or bananas or maize or rice, because they would have provided more calories than I could eat without gaining weight. Now I no longer have any restrictions on what I may eat, based on the energy content, returning to how it was when I was using lean meat as the main source of proteins, when I could eat much more varied vegetables and fruits than when I was eating only vegan food.