The Jive on Java: How Caffeine Boosts Metabolism and Helps Weight Loss

We know the headline caught your attention. People are constantly asking us about the effects of caffeine and whether they should kick the coffee habit once and for all. What we tell them might surprise you. Caffeine is not all bad – it does help increase metabolism and, in turn, this helps facilitate weight loss. Now, does this mean that ingesting large quantities of caffeine with hopes of trimming down is the way to go? Of course not. As with most things in life, too much of a good thing is not necessarily better.

Why do we believe that caffeine boosts metabolism and aids in weight loss?

For starters, one recent study published in the International Journal of Sport Nutrition and Exercise Metabolism showed that athletes who took in caffeine pre-exercise burned about 15% more calories for three hours post-exercise, compared to those who ingested a placebo. This suggests that the effects of caffeine, namely raising heart rate, does help burn calories, which, in theory, should assist in weight loss. Please understand that a conclusive study proving this has not yet been done; so these results have given rise to a theory, rather than conclusive fact.

So how can you take advantage of caffeine for weight loss?

Well, the previously mentioned study suggests that about 300 mg of caffeine (which equates to a cup and a half or so) before exercise actually has an effect on on post-exercise metabolism. This may be one reason why people find their morning workouts more beneficial. You, too, may consider moving your exercise routine to morning hours if you start your day with a Cup a Joe.

Many people also tout the benefits of green tea for weight loss. In that green tea is a source of caffeine, it is likely to have some effect similar to that mentioned for coffee. There may be other substances in green tea (something called catechins) that also promote weight loss, though this is less established. This does not mean that taking huge amounts of green tea extract is safe or useful. Rather, green tea may be your chosen source of caffeine. We advise it be used in its natural form (as tea), not in various products claiming to have super high concentrations of its distilled contents.

Doesn’t caffeine cause dehydration?

Here’s another “well, yes . . . and no” answer. In the short term it does. So, taking a big dose of caffeine such as one provided in an “energy drink” if it is not your typical fare, does lead to an immediate loss of bodily fluids (you might have noticed that you tend to pee a lot after ingesting caffeine). However, studies also have shown that people who ingest caffeine chronically in a routine manner develop a mechanism to adjust to the caffeine intake and lose less water. Therefore, a regular coffee or tea routine (in moderation) should not ultimately lead to dehydration. But, using large random doses of caffeine in the form of energy drinks or other energy boosting tablets/gels, etc. is not ideal as it will likely impact your workout and subsequent hydration status negatively.  Learn more about vitamins for hydration, and consider taking a vitamin for energy without high doses of caffeine.  Our brief vitamin quiz can help you figure out which vitamins to take. Taking proper electrolytes without excess caffeine can go much further towards hydration.

Does caffeine have other benefits?

We know caffeine helps memory in the short term (not Short Term Memory), meaning taking it before learning new info seems to help with some retention of that info. What we don’t know for sure is whether it helps preserve memory over a lifetime. Some have theorized that caffeine has a role in preventing dementia. Learn more about what vitamins to take for memory. So, perhaps that cup of coffee is worth having. Caffeine’s role in cancer, heart disease and bone density remains uncertain with various conflicting studies out there. More info is sure to arise in the future.

What are the negative effects of too much caffeine?

As we’ve said before, too much of a good thing is not always better. The side effects of excess caffeine can range in severity from annoying to lethal. Along with activating your central nervous system (thus the great effects on alertness and memory), it also activates your cardiovascular system. In turn, this can cause your heart rate to go up, producing palpitations (or in rare cases it can bring on dangerous arrhythmias). Likewise, the stimulation can contribute to high blood pressure.

There have been several reported cases of seizures and death after ingesting large or unknown quantities of caffeine containing energy products. This, of course, raises the concern that the mega doses available in these forms is not safe and should be avoided. There are added concerns when combining “energy” in the form of caffeine with alcohol. None of the energy products are FDA regulated, and it is of great concern that their contents are not rigorously tested.  More on supplement safety here. It is our belief that caffeine from naturally derived sources (coffee, tea, chocolate and the like) is much less risky because it is hard to overdose.

The obvious side effect of too much caffeine is insomnia or interrupted sleep. What many do not realize is that this can be a delayed effect, lasting 12 hours or more after you ingest it.

Another less recognized issue with caffeine is the rebound headache. Caffeine has effects on blood vessels in the brain which reverse migraines. Caffeine is in fact a common ingredient in over the counter migraine medications. It is useful for this purpose. However, the downside is that people who ingest caffeine regularly, are prone to withdrawal headaches when they stop. The best way to address this is to moderate your intake and wean down if needed to a lesser amount that does not lead to this rebound effect.

How much caffeine is safe to have and in what form?

A daily maximum of 400mg of caffeine is advised. See chart below for typical sources. Do recognize that not all coffee is created equal. A Starbucks dark roast packs a greater punch than your typical Folgers (a Starbucks tall brewed coffee is reported to have about 260mg per 12 oz, which far exceeds the typical cup of coffee listed below–this is in part due to the larger size of 12 vs 8 oz). Note that the table below consists mainly of natural sources (other than the sodas). These are likely a safer way to obtain caffeine than via high dose energy drinks or supplements. If you need energy for a workout, get it via electrolytes and other less harmful vitamins such as the B vitamins (try our PowerUp™ which contains no caffeine or sugar).

We also advise you to stop caffeine intake after 12 noon to minimize its impact on sleep at night. Its effects on sleep quality and duration can be subtle, but take their toll. More on vitamins for sleep here.

If you are using caffeine because you are tired all the time or feel like you need a rush of energy to get you through the day, consider other causes for feeling like this. Various medical conditions could be responsible (check with your doctor) as can poor quality or length of sleep, or various vitamin deficiencies. Take our vitamin survey to obtain a Personalized Multivitamin that may address these issues.

So enjoy that cup (or two) of Java each morning before you work out , but otherwise limit your intake.

Also, beware of the fact that many of today’s specialty coffee drinks are paired with loads of sugar and fat. These can be a huge source of hidden calories that, if left out, can aid in a plan to lose weight.

Caffeine Content of Common Sources(credit: WebMD)

Caffeine Sources

Approximate Caffeine Content (mg)

Coffee, regular (1 cup)


Espresso (1/4 cup)


Cappuccino, regular (1 cup)


Latte, regular (1 cup)


Tea, brewed, hot (1 cup)


Nestea Iced Tea, Earl Grey (1 cup)


Cola soda, regular or diet (12 oz)


Mountain Dew (12 oz)


Chocolate, semisweet (1 oz)


Chocolate milk (1 cup)


Cocoa powder (1 tablespoon)


Also check out these less obvious sources of caffeine found today, including things as surprising as sunflower seeds and oatmeal (of course marketed as energy products)!,,20313656_2,00.html

Romy Block specializes in Endocrinology and Metabolism and is mother to three active adolescent boys. Arielle Levitan is a Doctor of Internal Medicine with a special interest in Preventive Medicine and Women’s Health.  She is a mother of three teenagers. As professional women with active family lives, they recognize that people often neglect their own health needs and are uncertain about what vitamins to take. Each person is different in her diet, exercise and health history, and will benefit from different nutrients.  After years of advising their patients about the proper vitamins to take,  Drs. Block and Levitan created Vous Vitamin® to provide people everywhere with quality vitamins that are suited to their individual needs. They are authors of the award winning The Vitamin Solution: Two Doctors Clear Confusion About Vitamins and Your Health (She Writes Press, 2015). Take your vitamin quiz now to get exactly the right vitamins for your needs.

The statements made in this article have not been evaluated by the Food and Drug Administration. The products offered by Vous Vitamin® are not intended to diagnose, treat, cure, or prevent any disease.

Nothing contained herein is intended to be a diagnosis or constitute medical advice.  The symptoms described in this Blog may be a result of a serious medical condition which requires medical treatment.  You should consult with your doctor if you are experiencing any of the symptoms mentioned in this Blog and before beginning any vitamin or supplement regimen.




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