Shutterstock grilled salmon and asparagus

We often hear that diets don't work, or just don't last — depending on how disciplined you are. The best most of us can do is to just try to make healthy choices, based on a diet rich in whole foods, plenty of lean protein and fresh fruits and vegetables. Right?

Wrong, says Lyn-Genet Recitas, a New York-based nutrition expert and author of the popular yet controversial new diet book The Plan.

Recitas, who has studied holistic medicine and nutrition for more than 30 years, says there is no such thing as "healthy" foods. She argues that many foods we think are good for us, such as salmon and asparagus, can actually make us gain weight, because of the inflammatory response they trigger on an intestinal level, which can cause gas, bloating, weight gain and even diseases.

Recitas told Dr. Oz that eating one "reactive" food, can cause you to gain anywhere from half a pound to two pounds, almost instantly.

Story continues after slideshow:

The 'Devil Foods' See Gallery

"The most frustrating part of this is that you've probably been eating the very foods that are setting the whole inflammatory process ablaze in your body—without knowing it," Recitas says in the book, which outlines a 20-odd-day plan to find out which foods you should be avoiding based on your personal body chemistry.

As a guideline, Recitas also provides lists of which foods are more and less reactive, based on the results of thousands of her clients. Some of the most "toxic" foods include farm-raised fish, deli meats, sushi, greek yogurt, grapefruit and hard-boiled eggs. Surprisingly, some of the least-reactive foods include our guiltiest pleasures such as chocolate, bread, cheese and red wine.

The book's cheat-sheet on "devil foods" includes a list of ingredients we thought were actually good for us but are "tried-and-true reactivity nightmares," according to Recitas. "There's reactive and then there's wildly reactive," she says.

LOOK — So-called devil foods:

Oatmeal: Oatmeal, which is 85 per cent reactive in The Plan, is often said to lower cholesterol. However, Nutrition expert and author Lyn-Genet Recitas says it can also act as an inflammatory food, that can actually end up raising cholesterol levels.

Salmon: Recitas and her team found salmon was also highly inflammatory for some of her clients (85 per cent reactive). "Salmon is a fish rich in oils. As soon as you cook fish oil, you start to change its structure, potentially making it inflammatory."

Asparagus: Asparagus, also at a 85-per cent reactive level, can cause some people to gain weight, Recitas says.

Tomato Sauce: Tomato based products like ketchup, salsa and tomato soup are also part of this list. "Most canned or bottled tomato products contain citric acid, which further increases the acidity and exacerbates arthritis, psoriasis, eczema and acid reflux," she says.

Tofu: Through Recitas's research, she has also found her clients highly reactive to soy products. "Soy interferes with estrogen levels and deactivates the thyroid," she says.

Black Beans: Unlike chickpeas, which are considered low reactive, black beans are also as high as 85-per cent reactive. "Anything that causes gas is a signal that the body is having a hard time digesting that food, and black beans are notorious for this," Recitas says.