Why do we overeat? Why do we ever stop eating?

I’m going to use some summary quotes from a series at Gnolls.org about hunger and satiety signals. I just wanted to get some general points across that I have been talking about for some time now, and these bullet points pretty much sum it up perfectly. They relate nicely to my points about nutrient density, and your body’s ability to regulate it’s own nutrient and hunger needs if you allow it. (Check out my archives for more.)

Introductory points

• Hunger is not a singular motivation: it is the interaction of several different clinically measurable, provably distinct mental and physical processes.
• In a properly functioning human animal, likes and wants coincide; satiation is an accurate predictor of satiety; and the combination of hunger signals (likes and wants) and satisfaction signals (satiation and satiety) results in energy and nutrient balance at a healthy weight and body composition.
• Restrained eating requires the exercise of willpower to override likes, wants, and the lack of satiation or satiety; the exercise of willpower uses energy and causes stress; and stress makes you eat more. Therefore, a successful diet must minimize the role of willpower.
• A lack of satiety will leave us hungry no matter what else we do to compensate. We fail to achieve satiety by not ingesting (or not absorbing) the energy and/or nutrients our body requires, and by an inability to retrieve the energy and/or nutrients our bodies have stored due to mitochondrial dysfunction.
• Satiation is an estimate of future satiety based on sensory input. As with satiety, we fail to achieve it by not satisfying our nutritional needs. We can also bypass satiation by decreasing sensory exposure to our foods. Some common enablers are eating quickly, eating while distracted or on the run, and eating calorie-dense packaged and prepared foods.
• The role of reward in hunger constitutes hedonic impact (“liking”, palatability) and incentive salience (“wanting”, the drive to consume more food). The process of learning modifies both. Furthermore, reward is not limited to food, is neither static nor an intrinsic property of the food itself, and is modified by many experiences besides its taste during the act of consumption.

Conclusion Points

• Reward systems drive all our behaviors, not just our food preferences.
• Liking and wanting don’t exist just to make us fat: they exist to keep us alive.They are the product of millions of years of natural selection, during which animals that didn’t have our tastes died out and were replaced by those that did.
• Liking and wanting are values we assign to food, not invariant or intrinsic properties of the food itself.
• The modulation of reward (liking and wanting) does not require taste at all.
• Incentive salience (“wanting”) is a product of hedonic reward (“liking”), satiation, and satiety.
• Eating food you like may either decrease or increase your want for more, depending on the food, the circumstances, and whose studies you believe.
• Palatability can affect satiation, either via nutritional satiation or “sensory-specific satiety”, but it does not affect satiety.
• Hyperpalatability is an unnatural amount of hedonic reward, combined with an inability to produce satiation or satiety. Therefore, the worse a snack food is for you, the more difficult it usually is to stop eating. 
• Conclusion: in order to keep incentive salience (“wanting”) under control, make sure that hedonic impact (“liking”) is always accompanied by nutrition. Eat delicious but nutritionally dense foods, containing complete protein, healthy fats, and ample nutrients. Otherwise you’re eating food with no brakes.
• And when you do take the risk, eat your cheat food after you’ve already satiated yourself with a complete meal.

…Just sayin’