When it comes to stimulating our brains, Dr. Kessler noted, individual ingredients aren’t particularly potent. But by combining fats, sugar and salt in innumerable ways, food makers have essentially tapped into the brain’s reward system, creating a feedback loop that stimulates our desire to eat and leaves us wanting more and more even when we’re full…restaurants and food makers manipulate ingredients to reach the aptly named “bliss point.” Foods that contain too little or too much sugar, fat or salt are either bland or overwhelming. But food scientists work hard to reach the precise point at which we derive the greatest pleasure from fat, sugar and salt.
Well - How the Food Makers Captured Our Brains - NYTimes.com