Sometime in the semester, I heard people speak about satiety (satiation is the process of feeling full & terminating food ingestion during the course of eating) in relation to protein and fat (protein apparently is more satiating, even though fat has more calories). Feeling of fullness is important- it is one of the problems I faced as a raw vegan, which made sticking to the lifestyle very hard long-term (I was raw vegan for ~2 years).
So instead of preparing for class tomorrow, I am reading up on satiety! Some main points:
Most importantly- it’s not all about the calories, since not all calories are treated equally by the body. The hierarchy of fullness is the following: Protein > Carbs > Fats. So, protein satiates more than carbohydrates, and fat is least satiating (which came as a surprise to me considering it has most calories per weight). High-fat foods have a weak effect on satiation.
Within the macronutrient categories, we find differences too: not all carbs exert the same effect on satiety (fiber has been consistently shown to have a higher satiety value vs. simple sugars), and neither does fat (the medium-chain triglycerites [e.g. the wonderful coconut oil] seem to be more satiating).
Of course, people don’t eat only to get full. The number 1 reason given for eating a certain food is taste. More specifically- palatability (subjective pleasantness of food). Low-energy-dense foods tend to be less palatable, but more satiating 
According to the article*, ideally our diet would consist of low-energy-dense foods with high palatability (unfortunately such foods are not very common). This “diet” is one low in fat, has adequate protein and fiber, and includes lots of fruits, vegetables (so food with high water content).
Of course, focusing on whole foods vs. processed makes lots & lots of sense- a whole food product takes time to chew and digests longer (satiety signals are maintained for longer).
Apart from specific studies, common sense must prevail: staying away from “fat” is not necessary (not as much as staying away from processed fat, vegetable oils, etc…), and adding great fats (e.g. avocado!) to meals is both healthy and filling (studies show that while fat on its own is least satiating, it’s power to fill us up increases when it is added to carbs).
Feeling full is important! Constantly feeling deprived could potentially lead to overeatingand more stress.
P.S. I shall probably post more on the subject of satiety later, considering I have a whole class coming up on this topic 😀
*Gerstein, D. E., Woodward-Lopez, G., Evans, A. E., Kelsey, K., & Drewnowski, A. (2004). Clarifying concepts about macronutrients’ effects on satiation and satiety. Journal of the American Dietetic Association, 104(7), 1151–3. doi:10.1016/j.jada.2004.04.027
Mariya V. PhD 