I think I have to intervene here before someone takes dietary advice from the previous comments. Most of the statements made here are either false or there is nothing scientific behind them to support the claims.
Note that I am no dietetician myself either, but I have researched the topic extensively and even tested on myself.
The formula for weight gain:
calories in - calories out = net calories
if net calories > 0 => gain fat
Simple as that. Does not matter what, how or when you eat. For pure weight loss only calories count.
You can either increase the "calories out" by moving more or reduce "calories in" by eating less or eating less calorie-dense foods.
Why are we fatter than the nobility of the middle ages?
- Modern foods are produced to be energy rich. Refined sugar in the middle ages was rare (and it existed only in the form of syrups, honey and such which are slightly less calorie-dense than pure sugar) and in the modern age it is added to almost everything. Sweet tooth was mostly satisfied with fruits (which we tend not to prefer when we have to choose say, between an apple and chocolate) which are not very calorie-rich either. Our modern grain products are more refined (= more starch-rich = more energy per unit weight) than they were in the middle ages. In the middle ages fat was mostly within meat, nuts and vegetables. Our foods these days contain more fat in the form of added oils (eg. fries).
- We have easier access to high energy natural foods. Nuts, dates, fatty meat. Easily accessible by anyone and these were probably a rare sight even among nobility.
- Lack of new world food. Middle ages Europe had a pretty bleak variety of vegetables. Imagine a world where your veggie choices were pretty much low calorie squashes (forget pumpkins!), leafy and root vegetables. Forget the potato family (eg. tomato) and other more caloric veggies from the new world.
- Higher average caloric expense per person. Middle ages had crude transportation, which was mainly horses. Riding horses burn much more calories than driving cars. Pretty much all hobbies back then involved physical activity (archery, swordsmanship, hunting etc.)
