The Dark Side to Thylakoids and Other So-called Appetite Suppressants

Thylakoids come from green leaves, not from outer space or from the lab of a mad scientist. Thylakoids are making headlines as a natural appetite suppressant, but before you buy into the idea that they can help you with your weight, wait – take a look at the fine print to Thylakoid Magic.

Green-Eyed Insight on Appetite Suppressants:Thylakoids

Food Science in the News – Oct 23rd, 2013

The Findings

This is what you’ll see in the headlines:

“Thylakoids are natural appetite suppressants; they promote weight loss by controlling hunger hormones”

Natural Health Advisory article on thylakoids

“Eat greens and Lose Weight”

Doctor in the Kitchen Blog – Thylakoids

The Research

Notice how scientific studies have very descriptive titles. That’s pretty typical in the science-world because scientists know some people will only read the title of the paper it took them 3+ years to write and publish:

Supplementation by thylakoids to a high carbohydrate meal decreases feelings of hunger, elevates CCK levels and prevents postprandial hypoglycaemia in overweight women

Science Direct Access to this article

The Details

Overweight women (not lean, healthy people with their appetites in check and no weight to lose) were given a high-carb breakfast. The women who had thylakoid powder mixed into their blackcurrant jam (henceforth “special jam”) had decreased feelings of hunger and elevated CCK levels. CCK is the “satiety hormone” so an increase in CCK helps you feel fuller, longer.

This study was single-blind, meaning the scientists knew which women got the “special jam”. This study was also randomized, meaning every patient got the chance to eat the “special jam” one morning and the normal jam the other morning, but not every women got the special jam first. This is important because it eliminates “First Position Bias”. In other words, after you’ve been through Day One of the study, you know what to expect on Day Two. That might affect your answers on a “How Hungry Are You” survey or change your actions the night before you’re supposed to show up for the study.

The Bad Assumptions

The following statements are common in studies like these, but closer inspection shows they are more flash than substance, leading to confused consumers and frustrated food scientists:

ONE – The group that got more food reported less hunger than the group that got less food.

Hungry Study Stick FiguresIt seems rather obvious but I’ve read papers that forget to control calories in this type of study.

For example, there’s the study wherein half the group got a sugary energy drink, the other half got water. The group that got the sugar performed better. Well no duh, the other group was starving because all participants had to fast the night before (not uncommon but hello, something to keep in mind when you’re testing the effects of an energy drink).

This Really Happened! Read this “Energy Drink Evaluation” study

Fortunately, this study on thylakoids did control for such things. The calories between the “special jam” and the normal jam ranged from 537-554 calories and the carb/fat/protein breakdowns for the whole meal were the same (71% carbs with 11g sugar, 16.9-17.9 grams fat, 28.4-29.6 grams protein).

TWO – When people eat before they eat food, they eat less food when they eat.

I know this sounds ridiculous but Google “foods suppress appetite” and guaranteed you’ve seen these headlines before! When people ate soup before a meal, they ate less at the meal. When people ate an apple before a meal, they ate less at the meal. When people drank a large glass of konjac fiber, they ate less at a meal. Now read the italicized statement above again and you’ll get it.

In this particular study, the thylakoids didn’t have any affect on how much the women consumed at that particular meal. In fact, even though the “special jam” did boost CCK (satiety hormone levels) more than the normal jam, there wasn’t a big difference between the two until 180 minutes after the meal. The bad news is thylakoids won’t prevent you from overeating unless you eat food (such as a green leafy salad) before you eat food (meaning your meal). The good news is A) this study was done in women, not just in lab rats, and B) the thylakoids COULD help the women consume less food at the NEXT meal. That brings us to the next unfortunate assumption.

THREE – This small effect will change the course of your whole day.

There are some actions we can take in the morning that significantly alter the course of the day: workout before work, eat breakfast instead of skipping it, put the cell in the glove box to remove driving hazard temptation…and so on. When it comes to one meal affecting the volume of food consumed at the next meal, I remain skeptical.


There’s no question eating leafy greens is good for you, so if you need to believe that thylakoids can help you eat less throughout the day then, by all means, add more leafy greens to your diet.

But if you really care about suppressing your appetite and eating less food throughout the day, remember this: Aside from Volumetrics and social cues, there are many factors that affect how much food is consumed at a meal.  One of my reasons for being skeptical about any appetite suppressant is that “Unit Bias” and “Portion Distortion” remove hunger from the equation. Portion Distortion is the frequent underestimation of calories in a serving, and this is well documented. Unit Bias is best visualized as one of those ginormous muffins or a tall can of Arizona Iced Tea. Just because it’s one container, doesn’t mean it’s one serving. Without addressing these external factors, it’s difficult to tell how effective any appetite suppressant will be for controlling and curbing appetite.

Estimating Food Portions is Hard

10 thoughts on “The Dark Side to Thylakoids and Other So-called Appetite Suppressants

  • Has it been clarified on side effects? I’ve noticed that the research on Thylakoids has mostly been conducted by the same or possibly friendly groups of scientists from Sweden’s U of Lund, which are affiliated with a company that produces Appethyl, i.e. thylakoid extract from spinach. A big red flag is that one of the studies showed a huge spike in post-lunch glucose followed by a fasting period ~ 3.5 higher comparing to the level of glucose in placebo intakers. I have found none of the followed by Appethyl studies. Would diabetics be concerned?

    Also, since it affects fat’s digestion – what about bile, bile ducts and liver? How these are sensitive to thylakoids?

    • Unfortunately, I can’t answer your questions because I am not an expert on this subject. My focus is on energy drinks and their ingredients. However, I do want to emphasize my skepticism for thylakoids and appetite suppressants in general for the three reasons I highlighted here in my post. I think my “bottom line” captures my thoughts on the matter but I’m happy to share your comment so that others may see these concerns you’ve articulated. Thank you for sharing your thoughts and the reference article, and thank you for reading – I hope you’ll explore other more recent articles on this site.

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