Not directly. There are no calories in the can to gain weight from. What can matter on a two or three can a day habit is the caffeine load cutting into your sleep, the drinks displacing water and real meals, and the cravings that show up later at the snack aisle. The sweetener question is real but smaller than most articles claim.
The short version: the can isn't the problem. The habit is. Two or three a day means a caffeine load that reaches into your sleep, and short sleep is one of the better-established links to weight gain there is. Everything else on this list is smaller.
If artificial sweeteners specifically are what you're avoiding, Hydrate uses monk fruit and stevia. Our energy powders use sucralose — we'll be straight about that below.
If you've been drinking zero calorie energy drinks daily and the scale keeps creeping, they might be part of it. But most articles on this get the order of importance backwards, leading with gut bacteria and ending with sleep. It's the other way round.
Why zero calories doesn't mean zero effect
A zero calorie energy drink swaps sugar for sucralose, aspartame, acesulfame potassium, or stevia. The caffeine and the B vitamins stay the same as the regular version. So the calorie math genuinely does change — you're not drinking 200 calories of liquid sugar anymore, and compared to a sugared can that's a real improvement.
What doesn't change is everything else in the can, and everything the habit does to the rest of your day.
The caffeine and sleep problem, which is the big one
A zero calorie energy drink typically carries 150 to 300mg of caffeine. Two or three across a twelve hour shift puts you somewhere between 300 and 900mg, and the last one is usually the one that does the damage — caffeine has a half-life of roughly five hours, so a can at 3 PM is still working at 8 PM.
Short sleep and weight gain are about as well established a pairing as anything in this area. Sleep affects appetite regulation, food choices, and how much you move the next day. If your drinking pattern is quietly costing you an hour of sleep a night, that's the mechanism worth taking seriously — not the sweetener.
The practical fix is timing, not abstinence: get your caffeine into the first half of the shift and stop.
Does the sweetener actually matter?
Honestly, less than the internet suggests, and the research is still moving.
Some studies have found artificial sweeteners can shift gut bacteria in ways that may affect how the body handles glucose. Others haven't. The effect sizes are modest and the picture isn't settled. Anyone telling you sucralose is definitely making you fat is ahead of the evidence, and so is anyone telling you it definitely isn't.
There's a separate idea that a sweet taste without calories trains you to want more sweet food later. It's plausible, some research supports it, and plenty of people report it. It's also very hard to separate from the fact that people drinking three energy drinks a day are usually not eating well in general.
Where this lands practically: if you've cut sugar and the scale hasn't moved, the sweetener is a reasonable thing to experiment with. Two weeks off it will tell you more than any study will. But it shouldn't be the first thing you change.
And to be straight about our own products: Before Work Fuel is sweetened with sucralose. Refuel uses sucralose and acesulfame potassium. If you're avoiding artificial sweeteners, those aren't the answer for you. Hydrate uses monk fruit and stevia, and it's the one product in our lineup that fits that requirement.
What the habit displaces
This one gets less attention and probably deserves more.
Every can is a drink you didn't have of water. On a hot shift you're losing sodium and potassium through sweat, and a caffeinated drink with essentially no electrolytes doesn't replace them. Mild dehydration produces almost exactly what hunger produces — and it also produces what fatigue produces, which is why people reach for another can.
Then there's food. A can on the way in instead of breakfast means the first real meal is lunch, and a large late dinner tends to follow. That pattern moves the scale more reliably than anything a sweetener does.
If hydration is the part you've been neglecting, Hydrate carries 500mg of sodium and 340mg of potassium per scoop, with no caffeine and no artificial sweeteners.
What about cortisol?
You'll see this one everywhere: high caffeine raises cortisol, cortisol drives belly fat, therefore energy drinks give you a gut.
Each link in that chain has something behind it, but the chain as a whole is a stretch. Caffeine does raise cortisol acutely, the effect blunts with regular use, and getting from there to a measurable change in where you store fat is a much longer leap than the internet makes it sound. It's not nothing. It's also not the reason your jeans are tight.
How to tell whether it's your drinks
Five questions. If three or more are yes, they're a fair suspect:
- More than one a day on workdays?
- Weight up over the last six to twelve months without much change in how you eat?
- Craving sweets more than you used to?
- Is the last one landing after 2 or 3 PM?
- Sleeping worse than you did a year ago?
The fastest way to find out is to change one thing for two weeks. Not all of them — one. Start with moving your last caffeine earlier, because it's free and it's the biggest lever on the list.
A cleaner version of the same habit
You don't have to give up caffeine. Most people just need fewer, earlier, measured doses instead of an all-day drip.
One scoop of Before Work Fuel is 150mg of caffeine, stated on its own line on the panel, plus 80mg sodium, 75mg potassium and seven B vitamins. No sugar. Mixed cold before the shift, and that's the day's caffeine handled — no second or third can, no 3 PM top-up eating into your sleep. It is sweetened with sucralose, so if that's your specific concern, this isn't your product.
For the full set of swap options, see what to drink instead of energy drinks. If the mid-shift crash is part of what's driving the second can, that mechanism is in why some work energy drinks make you crash hard. And for how to structure caffeine across a long shift, see our guide to energy supplements for long workdays.
Fewer cans. Earlier caffeine.
One measured dose before the shift instead of three across the day. 150mg of caffeine per scoop, no sugar, real electrolytes. Made in the USA, third-party tested.
Frequently asked questions
Do zero calorie energy drinks cause weight gain?
Not directly, since there are no calories in them. On a heavy daily habit the plausible routes are indirect: caffeine late in the day cutting into sleep, the drinks replacing water and meals, and cravings later on. Of those, the sleep one has the strongest evidence behind it.
Do artificial sweeteners make you gain weight?
The research is genuinely unsettled. Some studies find effects on gut bacteria and glucose handling, others don't, and the effect sizes are modest either way. If you've already cut sugar and nothing has changed, trying two weeks without artificial sweeteners is a reasonable experiment. It shouldn't be your first change.
Why do I feel hungrier when I drink zero calorie energy drinks?
Two likely reasons. A sweet taste with no calories behind it may leave you wanting sweet food later. And mild dehydration produces sensations easy to read as hunger — if a can is replacing water on a hot shift, that's worth ruling out first.
Does caffeine cause belly fat?
The caffeine to cortisol to belly fat chain gets repeated a lot and each link has something behind it, but the full chain is a stretch. Caffeine raises cortisol acutely and the effect blunts with regular use. Sleep disruption from late caffeine is the more concrete concern.
Do zero calorie energy drinks break a fast?
They contain no calories, so not in the strict sense. Whether the sweeteners produce an insulin response is debated and appears to vary between people. If you're fasting specifically for fat loss, water and black coffee remove the question.
Do zero calorie energy drinks cause bloating?
For some people, yes. Carbonation, sugar alcohols, and certain sweeteners can all contribute, and more so on multiple cans a day. If it's a daily thing, changing one variable at a time is the way to find out which.
Is one a day okay?
For most healthy adults, one is unlikely to be the reason for a weight change. Timing matters more than the count — one at 5 AM is a different thing from one at 3 PM. The FDA has cited 400mg of caffeine a day as an amount not generally associated with negative effects in healthy adults, which one can typically fits inside.
What's the healthiest zero calorie energy drink?
The ones worth considering keep caffeine moderate rather than maxed, state the amount as a number rather than hiding it in a blend, and don't need a long additive list. Beyond that it's preference. For a full comparison on caffeine, sugar, and cost, see our guide to what to drink instead of energy drinks.
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