You may be aware of dark chocolate’s reputation for helping with weight loss. It’s an appealing idea, but is there scientific evidence to support this claim?
Some researchers have found that eating dark chocolate may have a positive impact on your blood sugar levels and will therefore reduce cravings for less nutritious foods later on.
Dark chocolate may also make you less hungry, thanks to its effects on a hormone responsible for regulating your appetite.
Although dark chocolate is generally a healthier alternative to other chocolate, it still contains sugar, and poorer quality dark chocolate may also have additives.
It’s best to choose a chocolate with a high percentage of cocoa — 70% and higher — and to eat it in moderation. But it's also important to know that how your body responds to food is totally unique to you.
A ZOE test can tell you about your individual responses to hundreds of different foods. The ZOE program can then help you to choose the right foods for your overall health, which in turn can lead to weight loss.
Take a free quiz to find out what ZOE can do for you, and read on to learn more about dark chocolate and weight loss.
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How dark chocolate may help with weight loss
Dark chocolate is generally higher in fiber and nutrients and lower in sugar than milk chocolate. There’s some evidence to suggest that the cocoa in it can contribute to weight loss, but the evidence is not very strong.
Cocoa contains substances called flavanols that may improve insulin sensitivity in people who have pre-diabetes.
Flavanols are a type of polyphenol, which are defense chemicals produced by plants that have been associated with a range of health benefits. They are antioxidants, meaning they help protect your cells from damage by free radicals, which are unstable molecules that can cause significant damage.
The cocoa in dark chocolate may also help you feel less hungry for longer by reducing levels of a hormone called ghrelin, which is involved in regulating appetite.
However, many of the studies on this topic have only included small groups of people. More research is needed to fully understand how dark chocolate impacts weight loss.
Better blood sugar control
Studies involving people with diabetes have found that eating dark chocolate is associated with improved insulin sensitivity and possibly weight loss.
Better insulin sensitivity means your cells are able to take up sugar from the blood more quickly and your blood sugar does not remain high for too long.
Spikes in your blood sugar can lead to dips or sugar “crashes.” These dips can lead to increased hunger and cravings, and are linked to obesity in the long-term.
More research is needed to fully understand the connection between dark chocolate and blood sugar control.
With over 1,000 participants, ZOE’s PREDICT1 study has shown that blood sugar dips that happen after eating are linked with:
higher calorie consumption (both at the next meal and over the next 24 hours)
less time to the next meal
But ZOE scientists have also found that blood sugar spikes vary hugely between people.
At ZOE, we know that understanding your personal responses to food — and eating the right foods for you — is good for your metabolic health and can lead to weight loss.
Unpublished research shows that people who closely followed their personalized ZOE program for 3 months lost an average of 9.4 pounds, while around 80% said they had more energy and didn’t feel hungry.
To better understand your unique responses to food, you can take a free quiz.
Improved appetite control
Dark chocolate is “a great way of satisfying your cravings for sweetness at the end of a meal without having too much,” says Spencer Hyman, chocolate expert and founder of the ethical craft chocolate company Cocoa Runners. He speaks on an upcoming ZOE Science Podcast.
Some very small studies appear to back this up, suggesting that eating dark chocolate — and even just smelling it — can reduce your appetite and lower the levels of the hormone ghrelin in your gut.
Ghrelin tells your brain that you're hungry. As you eat and begin to feel full, ghrelin levels decrease.
Other studies have found that people felt less hungry — and ate less food later in the day — after eating dark chocolate, compared with milk or white chocolate.
However, these were small studies involving specific groups of people, such as women who have gone through menopause. More research is needed to see whether this is also true in others.
What percentage of dark chocolate should you choose?
As we’ve seen, there’s some evidence that eating dark chocolate may influence your blood sugar levels and appetite in a way that’s been linked to weight loss.
However, eating too much of any one food is not the best choice for your health, and it’s important to be aware that even dark chocolate often has significant amounts of refined sugar added to it.
At ZOE, we don’t believe in counting calories or cutting out foods, but when selecting your dark chocolate, it’s best to choose one with a high cocoa content and to eat it in moderation.
The percentage of cocoa in dark chocolate can vary wildly, and the less cocoa it contains, the more likely it is to have high levels of sugar and additives.
Professor Tim Spector — scientific co-founder of ZOE and head of the twin research and genetic epidemiology department at King’s College London — recommends 70% dark chocolate as a good starting point.
“There’s no real consensus about what level of cocoa starts to be healthy,” says Prof. Spector. “But above 70% is where most people seem to draw the line.”
“The more cocoa you’ve got, the more fiber and polyphenols and more good stuff you’ve got in there. So you want to be getting up towards that high percentage if you can, particularly if you’re having chocolate on a regular basis.” — Prof. Tim Spector
If you currently love milk chocolate, you might want to slowly increase the percentage of cocoa in the chocolate you eat to help your taste buds adjust to the taste.
One way of doing this is by combining dark chocolate with other foods, such as fruit. Our research shows that food combinations can be very useful.
How much dark chocolate should you eat?
Despite its health benefits, even 70% dark chocolate contains added sugar.
The Dietary Guidelines for Americans recommend limiting added sugar to around 12 teaspoons, or around 48 grams, per day for women and to around 15 teaspoons, or 60 grams, for men.
While this may sound like a lot, keep in mind that this is the total added sugar in your diet from all meals, snacks, and beverages. But this does not include sugars that naturally occur in foods such as fruit and dairy.
If we break this down based on three meals a day, that's 16–20 grams of added sugar per meal. A 1-ounce, or 30-gram, serving has around 9 grams of added sugar.
Meanwhile, one review of studies looking at the effects of eating dark chocolate found that researchers generally gave participants a maximum of 20 grams per person per day.
That may not sound like much if you’re a chocolate lover, but given its potential for reducing your appetite, you might find that savoring a good quality dark chocolate satisfies your sweet cravings.
At ZOE, we have found that individual responses to dark chocolate vary widely across the population.
You can take ZOE’s personalized quiz to find out how you can discover your own unique blood sugar and blood fat responses to food.
Eating small amounts of dark chocolate may help to control your appetite by reducing levels of the hunger hormone ghrelin.
Flavonols in cocoa may also improve insulin sensitivity and blood sugar control, helping to prevent the “crashes” that can lead to eating more or choosing less healthy food options.
But more good quality research involving large groups of people is needed to strengthen these early findings.
With all the dark chocolate products on the market, it can be hard to know which ones are the best for your health. ZOE’s Prof. Tim Spector recommends choosing products that are at least 70% cocoa and that contain less added sugar and no artificial additives.
Even the best quality dark chocolate contains added sugar, so it’s best to eat it in moderation. Taking the time to savor dark chocolate can make it a great finish to a meal and may satisfy your sweet cravings.
At ZOE, we know that understanding your personal responses to food, and eating the right foods for you, is good for your metabolic health and can lead to weight loss without restricting what you eat.
Find out more about what ZOE’s at-home test can tell you about your unique body.
70% cocoa dark chocolate. (n.d.). https://fdc.nal.usda.gov/fdc-app.html#/food-details/2019539/nutrients
Appetite suppression through smelling of dark chocolate correlates with changes in ghrelin in young women. Regulatory Peptides. (2010). https://pubmed.ncbi.nlm.nih.gov/20102728/
Blood pressure is reduced and insulin sensitivity increased in glucose-intolerant, hypertensive subjects after 15 days of consuming high-polyphenol dark chocolate. The Journal of Nutrition. (2008). https://pubmed.ncbi.nlm.nih.gov/18716168/
Consumption of dark chocolate attenuates subsequent food intake compared with milk and white chocolate in postmenopausal women. Appetite. (2017). https://pubmed.ncbi.nlm.nih.gov/28572069/
Dietary sugars intake and cardiovascular health: a scientific statement from the American Heart Association. Circulation. (2009). https://pubmed.ncbi.nlm.nih.gov/19704096/
Effects of cocoa polyphenols and dark chocolate on obese adults: A scoping review. Nutrients. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7760201/
Effects of cocoa products/dark chocolate on serum lipids: a meta-analysis. European Journal of Clinical Nutrition. (2011). https://www.nature.com/articles/ejcn201164
Getting the facts: Added sugars (n.d.). https://www.cdc.gov/nutrition/data-statistics/added-sugars.html
Helpful or harmful? The comparative value of self-weighing and calorie counting versus intuitive eating on the eating disorder symptomology of college students. Eating and Weight Disorders — Studies on Anorexia, Bulimia, and Obesity. (2018). https://link.springer.com/article/10.1007/s40519-018-0562-6
Insulin translates unfavourable lifestyle into obesity. BMC Medicine. (2018). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6292073/
Understanding antioxidants. (n.d.). https://www.health.harvard.edu/staying-healthy/understanding-antioxidants
Use of dark chocolate for diabetic patients: a review of the literature and current evidence. Journal of Community Hospital Internal Medicine Perspectives. (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5699188/
Postprandial glycaemic dips predict appetite and energy intake in healthy individuals. Nature Metabolism. (2021). https://www.nature.com/articles/s42255-021-00383-x