How to measure after-meal fullness or befor-meal hunger

There are so called satiety scales helping to accurately esstimate how full people become after eating this or that food or meal.

Labelled Magnitude Satiety Scale

1 Greatest imaginable fullness
2 Least imaginable hunger
3 Bursting
4 Stuffed
5 Extremely full
6 Very full
7 Gorged
8 Surfeited
9 Moderately full
10 Extremely sated
11 Very sated
12 Very satisfied
13 Extremely satisfied
14 Extremely content
15 Satisfied
16 Slightly full
17 Very content
18 Moderately sated
19 Moderately satisfied
20 Moderately content
21 Slightly satisfied
22 Slightly sated
23 Slightly content
24 Semi-satisfied

Source: Cardello, A. V., Schutz, H. G., Lesher, L. L., & Merrill, E. (2005). Development and
testing of a labeled magnitude scale of perceived satiety. Appetite, 44(1),
1–13.

And here's are a couple of much simpler scale including 10 points for both satiety and hunger:

Hunger and Satiety Scale

0 - Ravenously hungry.
1 - Feel like ordering everything on the menu.
2 - Preoccupied with hunger, everything on the
menu looks good.
3 - Feel hungry and the urge to eat is strong.
4 - Feel a little hungry. Can wait to eat.
5 - Neutral, not hungry, not full.
6 - Sense food in your belly, could eat more.
7 - Hunger is gone. If you stop here, you may
not feel hungry for 3 to 4 hours.
8 - Not uncomfortable, definitely full belly.
9 - Moving into uncomfortable.
10 - Very uncomfortable, maybe even painful.

Source: Rockies and Univ. of Wyoming Coop. Extension Service, Family & Consumer Sciences.

Hunger/Satiety Scale
Developed by University of Illinois at Urbana - Champaign, 1998

1 = Famished, starving
2 = Headache, weak, cranky, low energy
3 = Want to eat now, stomach growls and feels empty
4 = Hungry - but could wait to eat, starting to feel empty but not there yet
5 = Not hungry, not full
6 = Feeling satisfied, stomach feels full and comfortable
7 = Feeling full, definitely don’t need more food
8 = Uncomfortably full
9 = Stuffed, very uncomfortable
10 = Bursting, painfully full

What fulness after a meal depends on?

One of the direction is studies into the so called satiety signals, which can decrease in the size of at meal. The most usual suspect was glucose: when its level drops in the time course after the previous meal, this drop is 'felt' by sensor cells in the brain resulting in sensations of hunger. (Ann NY Acad Sci 63: 14–42, 1955.)

Another candidate to satiety signals is one of ketone bodies (produced in the liver from body fat during fasting,even the overnight one,exercise, stress, or on a low carb diets. This ketone body is called beta-hydroxybutyrate and it reduced food intake after intra-venuos injection before meal. (Nutrition. 1999;15:704-714).

The meal used consisted of 250 g cooked vegetables, 35 g cheese, 50 g croutons and 25 g olive oil but for one group of volunteers, the meal was vegetable pieces in the broth they cooked in while for another group, the vegetables were homogenized, also with the broth, in a blender. The meal was significantly more satiating when in the homogenized form than when eaten in a solid–liquid state. It corresponded to longer time the food remained in the stomach and with higher levels of the "satiety hormone" cholecystokinin. (British Journal of Nutrition (1998), 80, 521–527)

Protein has been observed to increase satiety to a greater extent than carbohydrate and fat and can therefore reduce energy intake. Sleeping metabolic rate was significantly higher on a high-protein diet than the same-calorie, lower protein diet. Most importantly, the high protein diet resulted in increased use of body fat to cover the increased metabolic rate. Hunger sensation was higher especially during the evening and satiety was the higher the higher protein content of the diet. (American Journal of Clinical Nutrition, Vol. 83, No. 1, 89-94, 2006)

Glycaemic and insulin responses to carbohydrate foods are inversely proportional to the CCK response and satiety (Appetite. 1992 Apr; 18(2): 129-41)