The food reward theory is that our brain has evolved to want high-calorie foods for survival reasons so we gain a lot of pleasure from eating them. We had to work hard to obtain enough food calories; starvation was a real possibility. When pre-historic mankind found and ate high-calorie food, the brain released dopamine (food reward) to drive more of the same behavior.

In today's modern food environment, we suddenly have high-calorie concoctions everywhere you look and eating them provokes large releases of dopamine that the brain hasn't evolved to handle.

The effect varies but you could say a trigger food is any high-calorie food you have an exceptionally hard time staying away from, and/or a food that once you start eating it's hard to stop eating. The result is it can derail an otherwise successful diet.

For some people, a person's favorite trigger food is almost like a hit of drugs. It activates an internal switch and you can't flip it back.

One reason these foods are such a problem is that not only are they pleasurable, but they are not filling foods so the calories stack up extremely quickly without you noticing. Psychologically, you just want more and more... and your body never says "okay, I'm full".

Often, trigger foods are eaten for emotional reasons (see Emotional Eating).

Other times they're eaten out of habit. We just automatically reach for our favorite trigger food.

All that is why these types of foods are sometimes called "food with no brakes".

Types of Trigger Food

You probably already know what these foods are for you based on past experience -- each of us has our favorites. The main drivers are typically some kind of calorie-dense combination of sugar, fat, refined carbs/starch, and salt ... basically sweet or salty treats.

Trigger Food Examples: Chips, cookies, candy, candy bars, ice cream, brownies, chocolate, bacon, pizza. It's different for everyone but we all have those problem foods we love a little too much.

Food companies deliberately make these delicious foods -- aka, "junk food" -- because they know you'll buy it. (Nothing malicious: it's just how business works: if you didn't buy it, they wouldn't make it .. although in some cases food may be scientifically engineered to cause addictive-like behavior).

Some chemicals are more habit-forming and more inherently rewarding: alcohol, caffeine, and theobromine (in chocolate). The problem as far as weight loss (or weight gain) is concerned is that these chemicals often come packaged with other concentrated calories like carbs and fat (sugar, cream, etc). A single serving of some alcoholic drinks or energy drinks can be up to 300 - 500 calories. See Avoid Drinking Calories.

It's Easy to Gain Weight On Trigger Foods

Among other factors, studies have revealed two personal characteristics that make it more likely a person will gain weight or become obese: 1) Food is highly motivational 2) Impulsiveness or lack of self-control

If a person has both characteristics, he or she is more likely to overeat and gain weight. Essentially, if you find something really rewarding and you have poor impulse control, you're in trouble. On the other hand, there are many people who love food and find it highly motivating enough that they become "foodies", chefs, cooks and the like -- and stay lean -- because they have the ability to suppress or ignore urges and cravings that may come up.

Why "no-brakes" food leads to weight gain:

The fat content doesn't trigger fullness signals like other nutrients ("passive overconsumption")
It tastes fantastic, making it hard to stop eating (the pleasurable or hedonic system overrides our body's natural homeostatic system that normally regulates intake)
TEF (thermic effect of food) is lower than whole foods, which means you don't burn as many calories to digest and process it (which reduces energy expenditure)
Very low fiber content so you get hungrier sooner
Low protein content (not as satiating long term)
All of the above, plus the high calorie content

"Carb Addiction": Is carb addiction truly a real addiction? This is a debated area, but the fact remains that for some people, eating even a small amount of carbs makes them want to eat more. This may be more common with starches (bread or flour-based foods) but can occur with sugar as well. They may come attached with fat but the attraction seems to be the starch, or sugar content. The problems are the same as with any other "food with no brakes" - it leads to weight gain and difficulty in sticking to a diet.

Guidelines/Solutions (What To Do)

First of all, know this: you can still eat no-brakes food occasionally. See Occasional Indulgences. You're usually better off psychologically to not "forbid" yourself from ever eating something (unless you are or have been truly addicted, like an alcoholic, but that's rare for actual food).

It's possible to gradually move away from these foods over time. As you gradually stop eating them, your body chemistry will change and you won't crave them as much.

To start cutting back, keep no-brakes food out of your personal environment (don't buy it in the first place, or at least have limits).

You may need to spend some time on a low-carb or ketogenic diet for 3 - 6 weeks. This can reset taste preferences after which you can re-introduce various carbs without loss of control

Warning: It's very easy to reverse your effort and regain all your weight by trigger foods alone via gradual weight creep, even if you're also eating healthy foods.