While you may already know that dark leafy greens—like kale or spinach— are some of the most nutrient-dense foods in the world, it’s unlikely you’re aware of a compound in these veggies that acts as a natural appetite suppressant. Swedish researchers recently discovered that sac-like structures called thylakoids, which are abundant in green leafy vegetables, decrease feelings of hunger and increase satiety. By acting as a natural appetite suppressant, thylakoids could help you lose weight naturally, according the research published in the medical journal Appetite.[1] 

What are thylakoids?

Thylakoids are disk-shaped structures found within the chloroplasts of plant cell membranes. They contain the photosynthetic pigment, chlorophyll, which give leaves their green color, and they function as the site of photosynthesis, converting light into glucose.

How did thylakoids become known as natural appetite suppressants?

Researchers from Lund University in Sweden have been isolating and researching thylakoids since the early 1990’s. In 2009, Dr. Rickard Kohnke and his team at the “Appetite Regulation Unit” of the Department of Experimental Medicine, Lund University, Sweden, discovered that overweight mice on high-fat diets decreased their food intake, experienced significantly less weight gain, and had lower body fat when their high-fat diets were supplemented with thylakoid isolated from spinach.[2] Compared to the mice who did not receive thylakoid, they also had lower blood sugar levels and lower triglycerides. They also had higher levels of the satiety hormone cholecystokinin, a hormone secreted by the small intestine that helps digest fat and protein as well suppressing appetite.

Safe, natural appetite suppressant: Thylakoid research in humans shows alterations in three appetite-control hormones and insulin

Dr. Kohnke and his team then tested thylakoid in humans and found that it also acts as a natural appetite suppressant in normal-weight people.[3] Eleven subjects ate a high-fat meal (a sandwich with thylakoid-rich pesto or regular pesto). Afterwards, levels of three different appetite signaling hormones were altered in those given the thylakoid-rich sandwiches. Two hours after the meal, they showed significant increases in the satiety hormone cholecystokinin compared to those who did not eat a thylakoid-rich sandwich. They also had reduced levels of the hunger hormone ghrelin, a hormone secreted by adipose tissue (fat cells) that tells you you’re hungry. Six hours after the meal, they had significant increases in ghrelin’s opposite hormone—leptin—which also control’s appetite by telling you you’re full. The fact that thylakoid increased leptin levels in the blood six hours after eating is important because leptin is crucial for regulating calorie intake between meals and over longer periods of time.

Furthermore, insulin levels were reduced in those subjects eating the thylakoid-rich meal, while blood sugar levels remained unchanged. This means less insulin was needed to keep the blood sugar response normal in these healthy individuals. When the insulin response is exaggerated, such as in those with metabolic syndrome, you’re more likely to experience blood sugar swings with episodes of reactive hypoglycemia, leading to increased hunger a couple of hours after eating. Higher insulin responses are also associated with increased belly fat and inflammation, raising the risk of heart disease and other chronic diseases.

Latest thylakoid study shows this natural appetite suppressant could aid efforts to lose weight

The most recent thylakoid study conducted by the Swedish researchers helps to confirm thylakoid’s role as a natural appetite suppressant even more. This study, in overweight women, found that adding thylakoids to a high carbohydrate meal again decreased feelings of hunger and elevated the satiety hormone cholecystokinin. Twenty moderately overweight female subjects received test meals on three different occasions; two thylakoid enriched and one control, separated by one week. The test meals consisted of a high carbohydrate breakfast, with or without addition of thylakoids.

Based on blood samples and standardized questionnaires, the results showed that adding thylakoids to the subjects’ breakfasts suppressed hunger and increased secretion of cholecystokinin from three hours on. The thylakoids also prevented reactive hypoglycaemia (low blood sugar that results from insulin and blood sugar swings from high to low following a high-carb meal). “This study therefore suggests that the dietary addition of thylakoids could aid efforts to reduce food intake and prevent compensational eating later in the day, which may help to reduce body weight over time,” concluded the researchers.

How to get the benefits of this natural appetite suppressant in leafy greens

If hunger and cravings (especially after meals) are a problem for you in your attempt to maintain a healthy weight, remember to eat your leafy greens! You’ll not only be feeding your body with the most nutrient-dense foods on the planet, you’ll be regulating your appetite hormones in beneficial ways. While there are no thylakoid supplements yet on the market in the U.S., eating large servings of green leafy vegetables like spinach and kale will automatically increase your intake of this natural appetite suppressant. Nutrition experts like Dr. Joel Fuhrman, MD, author of the classic nutrition guide Eat to Live, for instance, recommend you eat at least one pound (16 oz.) of green leafy vegetables every day for optimal health and weight control. He may be onto something! Besides suppressing your appetite with leafy greens, there are a lot of additional weight loss tips natural health practitioners share with patients. You can read about ten of the top natural weight loss tips here.

[1] Appetite. 2013 Apr 27. pii: S0195-6663(13)00161-X.

[2] Phytother Res. 2009 Dec;23(12):1778-83.

[3] Scand J Gastroenterol. 2009;44(6):712-9.

Originally published in 2013, this blog has been updated.