The Wrong Eating Habits Can Hurt Your Brain, Not Just Your Waistline

Having been on a ketogentic diet (low carbs, high fat) for the last 5 months or so, this is in line with what I've seen.

I went on the diet because of the promise of a clearer head, as well as general health improvement. It made sense, as I'd been plotting my work efficiency with and without sugary products. The complete removal of all carbs has done nothing but improve my life.

The carb addiction component mentioned elsewhere lines up as well. At the beginning of the diet, there's a period called the keto flu that lasts a couple weeks. It's described as mental fogging, headaches, dehydration, etc. While this is also attributed to the switching of metabolic pathways (more water and electrolytes are needed daily), the effects were very similar to caffeine withdrawal.

And of course I indulged in sugar through the holidays, and found myself figuratively face down in a gutter each time ;)

> Fat and sugar (a carbohydrate) account for two of the three most common macronutrients, the third being protein. Eating a diet that's low in both fat and carbs would imply a mostly-protein diet which can lead to illness

Spot-on observation. Furthermore, while proteins can be metabolized for energy, that's not advisable as a major energy source, proteins should be spared for day-to-day repairs (most-all multicellular structures ---incl tissues/bones/organs/tendons, the brain, not just simply "the muscles"--- are constantly tearing-down and rebuilding and we also synthesize much other crucial stuff partially from amino acids, red/white blood cells, enzymes, the list goes on, even glucose if&as necessary) and burning them instead not just removes them as building materials but also creates various additional stresses on the body, produces extra detrimental waste products to be run through the kidneys and get excreted, etc.

All mammals excel at beta-oxidation of both carbohydrates and fatty acids for energy, I know of no animal thriving off the meagre amount of energy their bodies may safely obtain from proteins. Many humans don't seem do particularly well (in the long run) combining fats & carbs in ~equally high amounts and find better results emphasizing one and sharply reducing the other. (Personally I'm a fat advocate but no need to get into that discussion ;)

Consider 2000kcals from protein-only (not that your body will allow this) would require 500g of protein, so about ~2kg of super-lean meat or over 100 egg-whites.. and that's not yet counting any protein usage as building-blocks!

The "calorie is a calorie" argument is true in that

    weight gain/loss == surplus/deficit intake

Your point about sugar fucking with insulin balance and its addictive properties are good points, but not directly related to the study at hand. Western prepared foods are loaded with added sugar, but it's completely possible for obese people to eat a complete diet of home-cooked meals in surplus using only fresh, raw ingredients without a gram of added sugar. It's also completely possible for skinny people to eat shit food and not get fat. The researchers should have controlled for body fat % and diet, which would not have been challenging. Instead it seems they've chosen to completely conflate the two key factors.