Will a protein shake break my fast?
Q) Hey, I’ve heard you recommend having a protein shake before my morning workout. Doesn’t that break my fast?
A) I’ve been skipping breakfast for the past 10 years. Many of my online coaching clients opt to do that as well.
This is a style of intermittent fasting. And because I’ve written about it, people often ask me variations on the question, “Hey, won’t this break my fast?”
The answer is yes. After ANY calorie consumption, you will no longer be fasting. But the question is, does that matter?
I’d argue not.
Think about why you are fasting in the morning first place. For the majority of people, it’s to help you lose fat.
When you skip breakfast, this creates a morning “fasting” period that extends the time you haven’t eaten from the night before up until your lunch…
Something happens, and… fat loss!
So what is that something?
You may have heard that fasting lowers insulin levels, which helps you burn more fat.
But unfortunately, this is not the case.
And yes, I know there are a few so-called experts, Jason Fung, Gary Taubes, and their bazillion acolytes, who will try to convince you otherwise. (The same kinds of people will sell you on the idea that cardio when fasting will speed up fat loss.)
But they’re just making up a plausible-sounding mechanism to explain a result, so they can sell you books, pushing their low-carb conspiracy theories.
The only thing that helps with fat loss is sustaining a calorie deficit over time. Sustain is the key part of that.
Instead of having smaller meals, you can try skipping breakfast.
Many people who do this find that they no longer feel hungry in the mornings after around a week. And this allows them to have two, bigger, more satisfying meals while still having the same calorie intake as if they had three, smaller meals.
So, the purpose of the morning “fast” is to reduce meal frequency, which helps with appetite control, which helps you sustain a calorie deficit, which you need for fat loss.
Now, if having a splash of milk or a spoon of sugar in your morning coffee makes life better and your diet easier to sustain, please feel free to do that!
It adds little to your total calorie consumption, and that is what matters.
And yes, technically, this means you are no longer fasting.
But fat loss is not about fasting; it’s just a tool that may help you sustain a calorie deficit.
So, this is why I don’t hesitate to recommend to clients who train in the morning without eating anything prior to having a protein shake before their workout.
( See: Nutrient Timing Guide to Maximize Fat Loss and Muscle Growth)
It doesn’t matter that they are no longer technically fasting anymore, it’s more important for them to have amino acids in their bloodstream to minimize muscle breakdown. (Protein is made up of amino acids.)
( See: Why I recommend whey over BCAAs if training ‘fasted.’)
And yes, this is some additional calorie intake. But far fewer than a conventional meal, so you still get a calorie buffer to eat two bigger meals later on.
So to summarize, morning fasting CAN be a useful tool to help you sustain the calorie deficit you need for fat loss.
But it has nothing to do with insulin. You don’t have to fear “breaking” your fast. And if you don’t find that it helps, you’re not missing out.
Lastly, if you’re fasting for the claimed health benefits, I’d point out that the most impactful thing you can do for your health is to un-fatten yourself.
So, make sure you don’t put the proverbial cart before that hypothetical horse.
Thank you for reading.
WILL COFFEE BREAK MY FAST?
Black coffee has around 5 calories per cup. So this isn’t going to change any meaningful outcome.
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1 more question. I do understand the basics of IF. And able to apply it to my daily life. When I do decide to break it are times when I will have trekking or theme park trips where I will walk 15k ~ 20k steps.
What kind of breakfast I should be eating when I have a long day ahead of me, high fat- low carb or low fat- high carb?
Thank you.
High carb, low-ish fat.
Ok, I see…. Those days still be highly active throughout the day, similar to the training days.
Thank you.
Hello,
Is there any difference if someone chooses to skip out on lunch instead of breakfast?
Normally, I make myself a coffee oat shake with chia seeds for my breakfast. In the evening I workout after dinner. I still get about 7-8 hours of sleep.
Thank you.
Likely very little. If you’ve tried that, you’re finding it easier to sustain, do it. I’d have something after your evening workout before bed though. More on nutrient timing here: A Nutrient Timing Guide To Maximize Fat Loss and Muscle Growth
Hi Andy
One question still lingers. I train at home, about 20 minutes after waking for 20-30 minutes. I have breakfast about 30 minutes after training ends.
Is it then still recommended to get whey/BCAA/EAA in before (or during) training?
Thanks.
Hi Willem,
Best to do so yes. When we train, the body is going to seek amino acids. If they aren’t in the bloodstream already, it’ll break down muscle to get them. This is a very small percentage of muscle mass overall, and you will be eating 30 minutes after, so how much of a difference would this really make over the long run? I don’t know. But, better to have a scoop of whey if you can as it optimizes things.
Thinking about it another way, it’s not like the shipbuilders in armies 2000 years ago woke up and got to work carrying heavy shit without breakfast, and lost all their muscle mass. I am sure they were still big fellas. The point is, they could probably have been bigger if they’d had some food/whey prior.
Hi Andy,
Not sure if yo you pick these replies up but if you do, thank you.
This is exactly the type of no BS information that I for one need.
Thank you, John.
Indeed, debunking fitness industry BS is a never-ending game of whack-a-mole.
Most appreciate you taking the time to comment!
Hi Andy, I use pea protein as a vegan. I’ve read lots about whey pre- early morning workouts, which is when I workout as well- is my vegan protein “good enough” for that purpose?
Hi Kaleigh,
A 70:30 mix of pea and rice protein closely mimics the amino acid profile of whey. You can order custom blends from a number of stores, I’ve heard good things about True Nutrition.
This article may be helpful: Optimizing Vegan Diets for Performance and Muscle Growth
Big fan
Thanks for the motivation, man!
Very well articulated principle about fat loss and continued sustainable daily calorie deficit. After being conditioned for decades about rules and absolutes with nutritional plans I truly enjoy your posts and get much insight from them.
Thank you, Forrest!
Great advice. When my calories get down a little lower, definitely going to replace my normal breakfast with a shake so I can have a bigger dinner.
Solid idea. Most welcome.
What if you work out in the morning but don’t actually like to eat beforehand? Should I still have that protein shake? Hate the feeling of being full and working out.
Better to have the shake. A single-scoop whey shake won’t fill you up.
Pretty much the only fitness advice I listen to online these days

Honored!
Thank you. I fast from dinner 5pm to after my workout I’m the morning when I drink my protein shake at 7am. Sustained this diet for 5 years now. Works!
Glad you find it helpful, Ken!
As someone who uses fasting a lot (for myself–doesn’t work with everyone I work with) it’s just another signal/barrier to snacking. I will not be reaching for that handful of brazil nuts before 1pm because I’m not allowed to–especially when I don’t really ‘need’ it, they’re just sitting there.
Coffee with cream can help me delay eating my main meal by an hour or two so there’s probably a net calorie reduction there. Just a tactic as you always say!
Exactly. Thank you for sharing!
Very impressive, great knowledge and well delivered without being patronizing. Keep it up pls
Thank you!
Hey Andy, I’m a long time follower of your content, thanks for putting out so much info for free, big appreciation from me. Just recently read your protein powder article and was wondering if Optimum Nutrition and Dymatize are kinda equivalent, because I couldn’t find the leucine content on the 5lbs container I usually buy and was thinking of switching to Dyma. Any opinions?
Hi Eduardo, thank you. As I said at the end of the article (How to Avoid Protein Spiking Scams): “I will not make specific recommendations because a manufacturer can change the formula of their products at any time. Use this guide to make an educated decision on buying a product that is available to you at a reasonable cost and shipping rate in your country. I’m not here to make that decision for you.”
But also as I said, “If it’s not on the label you have no way to know, so best to buy something else.”
Very clear & succinct. Thank you. Also, very reassuring!
Thank you!
When would you advise fast acting carbs with the protein before an earlyish morning workout or is it not necessary ever?
Outside of special/weird circumstances, there isn’t really much need for the non-athlete to worry about it.
If MPS caps out at roughly 25g whey is there any reason to ever have 2 scoops?
It’s a myth that your body can’t utilize more than 25g of protein at once.
Of course. I guess my question is what benefit does it have/what else is it used for once that MPS cap is hit at the individual meal – which seems to be at about 25-50g depending on protein source.
That was a long-standing assumption, but some research at the end of last year would suggest otherwise: “The Anabolic Response to Dietary Protein Is Not Limited by the Maximal Stimulation of Protein Synthesis in Healthy Older Adults: A Randomized Crossover Trial”