Caffeinated beverages are incredibly prevalent in our society. I drink them. You probably drink them. Your mailman and produce clerk might be drinking them right now. The realities of caffeine and the effects it has on our bodies have been largely studied, but I think the practical implications are frequently misguided and misinterpreted. As with most things, caffeine consumption should be viewed on a spectrum; not as a good vs. evil debate as it frequently is. The words you’ll find below seek to answer pressing questions regarding caffeine consumption.
Before taking this deep dive, it should be known this information is intended for the healthy, adult population. I do not advocate for the use of caffeine at large, but I do advocate for responsibility and educated decision-making.
How much is too much?
As an avid coffee drinker myself, this is the question I needed answered above all others. A review performed by Helms et al(1) noted a safe range of consumption to be 5-6mg/kg/day for the healthy, adult population. Further research by Turnbull et al(2) asserted that up to 600mg/day could be consumed with little to no adverse effects. Practically, it stands to reason that sticking to the lower end of this caffeine spectrum be reasonable for those not accustomed to its consumption. A graphic of these recommendations can be found… well, right here.
The half-life of caffeine is 4-6 hours, meaning it takes 4-6 hours for the caffeine you ingested to be halved within your body. So, if you consume 200mg of caffeine with breakfast, you’ll only have half that much circulating in you by lunchtime. This number does vary widely among individuals, and it’s likely your body will become more efficient in clearing caffeine from continual usage, decreasing that affective window.
TAKE HOME: 5-6mg/kg/day seems to be a safe upper limit intake of caffeine.
Does it stimulate fat loss?
Caffeine is a stimulant, meaning the volume dial of your body’s nervous system is turned up from consumption. This manifests as many things, most desirably increased alertness and wakefulness. Something else to consider is your basal metabolic rate (BMR), which may be adequately defined as the total number of calories your body burns just to keep you alive. It’s turned up as well, though not to some groundbreaking level. This is why the weight loss pills you’ve seen advertised at 3am likely contain caffeine or some derivative of it.
The increase in BMR means an increase in calories burned…meaning an easier time with weight loss. Hooray! But keep in mind this effect is largely variable and likely to succumb to tolerance as well. Not to mention, pouring cream and sugar on your cup of Joe largely neutralizes this effect from a simple calories in vs. calories out perspective. Can it be useful? Yes. Can it be relied on? That’s a negative, Ghost Rider.
TAKE HOME: Caffeine increases basal energy expenditure slightly, but I would not recommend its use for the sole intent of fat loss.
Will it help my workouts?
Personally, I usually drink coffee twice per day; once in the morning and once before I head to workout. I decided to take a peak at caffeine’s effects both on endurance and strength training. From an endurance perspective, caffeine does appear efficacious to enhance performance by a slight margin. However, larger doses (3mg/kg) are normally required to see these effects(3). Also important to realize is that caffeine when taken with food will be absorbed into the system more slowly, prolonging the desirable ergogenic window.
From a weight training perspective, the results are a bit less convincing. A majority of the research I reviewed looked at max-effort tasks, which likely isn’t akin to the audience I’m speaking to(3). However, I do believe the cognitive and arousal benefits can only stand to benefit the lifter when undergoing lengthy workouts. Therefore, a safe recommendation is likely in accordance with the endurance team of 3mg/kg.
TAKE HOME: Caffeine, when consumed ~1 or more hours prior to exercise, does show performance benefits, but the dosage needed to see results is likely fairly high (3mg/kg).
How long does it take to become tolerant?
As per usual, it depends. It stands to reason that how much and how often you consume plays a large role here. Our bodies are very resilient, and when foreign chemicals invade, it does its best toe the line of homeostasis. Though there were no steadfast timestamps in the research, I think the important point to note is that tolerance to caffeine does exist. That is, both the desirable and undesirable effects of its consumption will regress toward normalcy with continual usage.
Such positive effects may include increased arousal and concentration while restlessness and acute increases in blood pressure may manifest as negative consequences. Tolerance, or desensitization as it were, dictates these effects will dissipate over time. I believe the practical takeaway here is that caffeine may be best cycled. That is, switching to decaf for a couple weeks or abstaining from caffeine on the weekends may be advantageous for chronic use.
TAKE HOME: There was no steadfast length of time to become tolerant to caffeine’s effects, but it is likely predicated on the amount ingested. I recommend cycling caffeine if physiological benefits are desired.
List of Common Caffeinated Products
For the sake of reference, I’ve included a table of commonly consumed caffeinated beverages below. Something that caught my eye when making this table was the difference in caffeine content between hot and iced coffee. Obviously, given an absolute amount of drink, there’s less coffee in the iced version to make room for said frozen water. However, this may be a practical way to reduce your own consumption if need be. Or maybe I’m just weird and enjoy iced coffee in the dead of winter. Your move.
*measurements taken directly from company website
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1. Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition. 2014;11(1).
2. Turnbull D, Rodricks JV, Mariano GF, Chowdhury F. Caffeine and cardiovascular health. Regulatory Toxicology and Pharmacology. 2017;89:165-185.
3. Mclellan TM, Lieberman HR, Caldwell JA. A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience and Biobehavioral Reviews. 2016;71:294-312.