You're 14 hours in, feeling sharp, and you reach for your supplement stack. Quick question: do you actually know what's in it? Plenty of products sold to people who fast carry calories, carbs or ingredients with a real insulin effect. That's not a disaster. It just isn't "fasted" anymore.
First, what "breaking a fast" even means
There's no official definition, which is why the internet keeps fighting about it. For most people doing intermittent fasting, the goal is pretty simple: keep calories near zero and let insulin stay low between meals. So the useful question isn't "is this technically food?" It's "does this bring in energy, or push insulin up in a meaningful way?"
Some things clearly do. Some clearly don't. And some sit in a grey zone where the honest answer is that we don't have great data yet.
The usual suspects
Maltodextrin and sugars. Maltodextrin shows up in a lot of powders as a filler or carrier, and it isn't calorie-free. It's a digestible carbohydrate, and a review in Critical Reviews in Food Science and Nutrition points out that the glucose from it gets absorbed quickly. If it's on the label in any real amount, you're drinking carbs. Same story for gummy vitamins and anything sweetened with actual sugar.
BCAAs and amino acid blends. They get marketed as "fasted training" support, but amino acids aren't neutral. A 2020 review of human studies found that oral BCAAs and leucine raised insulin in healthy people even without carbs on board. They also carry calories. Sipping BCAAs all morning puts you in a different state than water would.
Protein and collagen. Same logic, more calories. Great once your window opens. Not a fasting drink.
Proprietary blends. The issue here isn't one specific ingredient. It's that you can't see what's in there or how much. If a brand won't show you the amounts, you have no way to judge what it does to your fast.
What's generally fine
Plain electrolytes. Sodium, potassium and magnesium salts don't carry calories. Your kidneys tend to let go of more sodium once you stop eating, so topping it up can make sense, especially if you train or sweat a lot. More on that in The Electrolyte Problem Nobody Talks About When Fasting.
Creatine monohydrate. It isn't a carb, a fat or a protein, and a standard serving is usually labeled at zero calories. We haven't seen good evidence that creatine on its own triggers a meal-like insulin response. We also haven't seen studies that tested it directly in people mid-fast, so we won't pretend that question is closed. What's well established is that creatine works through consistent daily use, so if you'd rather play it safe, take it with your first meal. The full breakdown is in Creatine and Fasting: The Science You Need to Know.
How to read a label in 30 seconds
- Check calories and total carbs first. Anything above zero means something in there is food.
- Scan the ingredient list for maltodextrin, dextrose, sugar, fruit juice powder, amino acids or protein.
- "Proprietary blend" with no amounts? Treat it as a question mark.
- Look for actual numbers next to each mineral. "Contains electrolytes" tells you nothing.
In practice
Keep your fasting window boring. Water, black coffee or plain tea, and electrolytes if you need them. Move amino acids, protein and anything with carbs into your eating window. Take creatine whenever you'll actually remember it, and don't stress about the clock.
If a product's label won't tell you exactly what's inside, that's your answer.
That's the thinking behind Lyte & Loaded, the electrolyte and creatine drink we're building: zero sugar, zero calories, every ingredient on the label. It isn't out yet. If you want a heads-up when it lands, join the waitlist.
Feed the mission. Not the hunger.
This article is for information only and isn't a substitute for advice from a health professional.
Sources: Hofman et al., "Nutrition, Health, and Regulatory Aspects of Digestible Maltodextrins," Critical Reviews in Food Science and Nutrition, 2016; van Sloun et al., "The Impact of Amino Acids on Postprandial Glucose and Insulin Kinetics in Humans: A Quantitative Overview," Nutrients, 2020; DeFronzo et al., "The effect of insulin on renal handling of sodium, potassium, calcium, and phosphate in man," Journal of Clinical Investigation, 1975; Kreider et al., "International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine," Journal of the International Society of Sports Nutrition, 2017.