If you’re one of the millions of Americans trying to shed a few pounds, you’ll be happy to hear about this new food discovery. A little-known class of natural chemicals found in certain foods may help you keep your weight down – without cutting calories or limiting what you eat.

So few people know about these substances, it seems to me they’re pretty much a secret.

But they shouldn’t be. Because they’re a dieter’s new best friend, thanks to the way they affect metabolism and change the way your cells burn calories. And this gets even better: they can improve your health in other ways, because these antioxidants keep your immune system behaving properly and limit harmful inflammation.

Flavonoid Power

When Harvard researchers investigated the foods eaten by more than 120,000 men and women taking part in three long-term studies over a period of 24 years, they found that fruits and vegetables rich in pigments called flavonoids limited how much weight people gained, or helped them maintain their weight at the level it was at the beginning of the study.1

But not all flavonoids had an equal effect on weight. Among these natural chemicals, the study showed that what are called anthocyaninsflavonoid polymers and flavonols provided the most powerful benefits.

Anythocyanins are pigments that give foods a red, blue or sort of violet color. In the Harvard study, the most popular foods rich in anthocyanins were strawberries and blueberries.

Sources of the other weight-limiting flavonoids include beans, lentils, oranges, apples, pears, onions, tea and berries.

Yo-yo Dieting

Aside from helping you lose weight or keeping you from gaining it, research shows that flavonoids may be the key to breaking the up-and-down, yo-yo, weight-loss-weight-regain cycle.

This research, performed in Israel, also indicates that the types of probiotic bacteria living in your digestive tract affect your weight.

In a series of lab tests, the Israeli researchers found that the bacteria that thrive in your intestines when you are overweight don’t take kindly to your efforts to lose weight. After you take off pounds, they may sabotage your metabolism so that you burn fewer calories and find it much harder not to put the weight back on.

These hostile bacteria sabotage you in several ways. For one thing, the bacteria that want to keep you chubby work overtime at eliminating the flavonoids you consume so that these natural chemicals can’t help your cells burn off calories and eliminate fat tissue.

The way to fight back against these bacteria, say the scientists, is to smother them in flavonoids. Consume so many flavonoids that the bacteria can’t eliminate enough of them to drive your weight back up.

“We call this approach ‘post-biotic’ intervention,” says researcher Eran Segal. “In contrast to probiotics, which introduce helpful microbes into the intestines, we are not introducing the microbes themselves but substances affected by the microbiome (probiotic bacteria), which might prove to be more safe and effective.”

Organic Weight Loss

Incidentally, if you want to maximize your consumption of flavonoids, eat organic.

Here’s an example of why:

A study in Ireland compared the flavonoid content of organic onions to conventional onions that had been raised with the use of pesticides. The study demonstrated that organic onions were significantly richer in these weight-controlling substances.2

After I read all this research on flavonoids, I started thinking that it’s no wonder people today weigh so much more than they did a few decades ago. Most of us have been eating processed foods devoid of flavonoids. The lack of these nutrients robs the body of a key tool it uses to keep weight under control and at a healthy level.

So it’s time for a throwback diet. Throw away the processed treats and start eating more whole foods including plenty of fruits and vegetables. You have nothing to lose but your waistline.


  1. http://www.bmj.com/content/352/bmj.i17
  2. http://pubs.acs.org/doi/abs/10.1021/acs.jafc.7b01352