It would be almost too good to be true that the world's most popular mood-altering substance would also help with weight loss.

But is there actual truth to this? Let’s find out.

What do experts say

While many popular, non-medical websites report caffeine does help with weight loss, Mayo Clinic says that the effects are probably minor and short-term. The esteemed medical institution reports that there may be minor weight loss associated with caffeine consumption, and perhaps some aid in keeping the weight off. [1]

If there is a causal connection, however minor, there are a couple of theories as to how it may work:

1. Caffeine may suppress the appetite by reducing feelings of hunger, which may prompt caffeine users to avoid eating for a time.
2. Caffeine increases the number of calories the body burns, even while resting, by stimulating thermogenesis or creation of the heat and energy that help digest foods.

Registered dietitian Katherine Zeratsky writes for Mayo: [1]

Some studies looking at caffeine and weight were poor quality or done on animals, making the results questionable or hard to generalize to humans. In addition, some studies found that even decaffeinated coffee may contribute to modest weight loss, suggesting that substances or factors besides caffeine may play a role in weight loss.

Dr. Bob Arnot told People magazine that caffeine consumption can increase human metabolism to the point where the body burns 100 extra calories per day. Sounds modest given Americans' calorie-rich, fatty diets. But in a year that's 36,500 calories! That equates to a weight loss of about 10.4 pounds a year because to lose 1 pound the body must burn about 3,500 calories. To extrapolate, in four years you could lose 41.6 pounds just from caffeine consumption. Though I hesitate to say a person could actually lose that much weight just from drinking coffee without proper exercise and diet. [2]

High-calorie beverages

Ms Zeratsky points out that if there is any connection between weight loss and caffeine consumption, it may be entirely canceled out if you drink beverages with a lot calories.

Starbucks, for example, is notorious for its high-calorie drinks. The 10 highest-calorie, 20-ounce drinks at the popular chain range from more than 500 to more than 600 calories, which would certainly negate any modest weight-loss or calorie-reduction benefit you might get from the caffeine they contain.

To know more about how much calorie there is on Starbucks drinks, watch this video:

The bottom line: Be cautious about using caffeine products to help with weight loss. When used in moderation (400 milligrams or less) by healthy adults, caffeine is generally safe. But too much caffeine might cause nervousness, insomnia, nausea, increased blood pressure and other problems.

Other benefits of coffee

While the jury of medical experts appears to still be deliberating about any purported weight-loss associated with caffeine, studies have shown it has a number of very beneficial effects on people. A New York Times article covered these studies, as follows: [3]

• A 2015 study of more than 1.2 million people found that folks who drink 3 to 5 cups of black coffee a day have fewer heart problems than those who drink none. People who drink 5 or more cups don't have any more problems than anyone else.
• Two other studies, meta-analyses that collated data from 11 other research articles, found that drinking 2 to 6 cups a day results in a lower risk of stroke disease. One of those meta-studies included data from more than 500,000 participants.
• A third study, another meta-study, found that people who drink moderate amounts of coffee have a lower risk of heart failure.
• A study looking at all cancers suggested that it might be associated with reduced overall cancer incidence and that the more you drank, the more protection was seen, a NewYork Times article on all these studies states.

If you want to learn more, here are 7 surprising benefits of coffee.

So does caffeine help with weight loss?

Let's allow the Obesity Action Coalition to have the last word on whether caffeine boosts weight loss: [4]

Some research has suggested that caffeine may stimulate thermogenesis - a scientific name for the way your body generates heat and energy from the calories in your food; but nutrition experts say that this effect probably isn't enough to produce significant weight-loss. Caffeine may also reduce your desire to eat for a brief time, but again, there's no good evidence over the long-term that this effect leads to weight-loss. To date, no conclusive clinical studies have been done to determine the long-term effect of caffeine on weight loss, and the smaller studies that have been done show a lot of variability in the outcomes.

In fact, the coalition gives a warning:

At present, even though caffeine may have a small effect on energy and appetite that could lead to some positive short-term effects on your energy balance, there's no evidence that it can actually cause you to lose weight. On the other side of the equation, excessive caffeine consumption clearly can be harmful.

So, while caffeine may or may not help with weight loss, as long as you don't consume too much it won't harm you and may actually provide a plethora of health benefits.

Sources

[1] http://www.mayoclinic.org/healthy-lifestyle/weight-loss/expert-answers/caffeine/faq-20058459

[2] http://people.com/bodies/drinking-coffee-weight-loss/

[3] https://www.nytimes.com/2015/05/12/upshot/more-consensus-on-coffees-benefits-than-you-might-think.html

[4] http://www.obesityaction.org/educational-resources/resource-articles-2/nutrition/upper-limits-the-value-of-caffeine-in-weight-loss