From Atlantic:
METHODOLOGY: A small experiment out of the University of Missouri involved 20 overweight or obese females, aged 18 to 20, who identified as infrequent breakfast eaters. Each morning for a week, the researchers had the participants eat either 350 calories of cereal (13 grams of protein), 350 calories of eggs and beef (35 grams of protein), or skip breakfast entirely. Dietary fat, fiber, sugar, and energy density were kept constant across all of their breakfasts.
Participants adjusted to their diets for six days. On the seventh day, they were kept in a lab so that researchers could track/control their behavior. They had them fill out questionnaires about their hunger levels and cravings. They took repeated blood samples. They hooked them up to an fMRI while showing them pictures of food. These tests were repeated on three different Saturdays.
On lab days, the participants were all given a standard 500-calorie lunch; for dinner they were given cut-up pieces of microwaveable pizza pockets and told to eat until they were full. They were then sent home with coolers packed with 4,000 calories worth of snacks: cookies, cakes, granola bars, candy (in its hard, chocolate, and gummy forms), chips, popcorn, crackers, pretzels, microwaveable mac and cheese, string cheese, fruits and veggies, single servings of ice cream, beef jerky, yogurt, and more microwaveable pizza pockets. This was meant to simulate the overexposure to and wide availability of snacks typical of the “modern food environment.”
RESULTS: Eating any breakfast was associated with increased feelings of fullness, a reduced desire to eat, and lower levels of ghrelin (a hunger-stimulating hormone) throughout the morning. But meaty, eggy breakfast was associated with these benefits over the course of the entire day. Participants who had a lot of protein in the morning also had reductions in their “cravings-related” brain activity, and increased levels of a hormone associated with satiety. They snacked less on fatty foods in the evening, as compared to those who ate cereal or nothing.
More here.