Which Liquids Are Allowed With Intermittent Fasting?
“I’m doing intermittent fasting. Is it okay to drink this during my fasting period?” Welcome to what I see in my inbox most days. Intermittent fasting is getting popular and with this popularity comes the alarming reoccurrence of this same question. Today I’m going to clarify exactly what is appropriate to drink while you’re fasting.
As with most things in health and fitness, there isn’t a clear-cut response as the answer truly depends on the reason why you’re fasting in the first place.
Additionally, there are different definitions of what constitutes a “true” fast.
What is Intermittent Fasting?
I know, you’ve heard this definition before, so if you know what fasting is then feel free to skip below to the good stuff.
Intermittent fasting is simple. Fasting involves periodically abstaining from food for 16, 18, 20 hours and sometimes for even longer periods of time.
Below are what I consider to be the most common variations of intermittent fasting:
16/8 or Leangains
16:8 or ‘Leangains‘ is a schedule of eating popularised by Martin Berkhan. This involves fasting for 16 hours and eating for 8 hours.
The 5:2 diet
The 5:2 diet involves taking two days out of the week (whether they’re consecutive is optional) and eating around 500 calories or 25% of your caloric intake on these days.
The warrior diet (20:4)
The warrior diet involves eating for 4 hours and fasting for 20 hours.
One meal a day (OMAD)
One meal a day, commonly known as ‘OMAD’ involves eating once per day. In general, this would take you around 2 hours and so it usually ends up as a 22:2 schedule.
Prolonged fasting involves fasting for over 48 hours, usually up to around 120 hours. Prolonged fasts have potential benefits on health that isn’t achievable during a regular fasting period.
What Is A “True” Fast?
To answer the question of which liquids are appropriate on a fast we must first ask the question, what constitutes a “true fast”.
For the majority of people fasting is practised in order to lose weight, although there are other benefits such as autophagy which is way better.
There are a few definitions for intermittent fasting:
1. The complete abstinence of food with or without water. No water is referred to as a dry fast (don’t do this).
2. Fasting protocols such as the 5:2 diet involve eating sparingly (300-500 calories) on a given day.
3. My definition of fasting is little to no food. If any food is consumed it must be the least insulinogenic.
Is Fasting Advantageous For Weight Loss?
You must always remember that intermittent fasting is no magic cure for weight loss. Always keep the hierarchy of needs in mind:
Calories -> Macronuteitns -> Micronutrients -> Timing (fasting) -> Supplementation
There is some evidence that suggests fasting may help promote more fat loss as opposed to weight loss, meaning fasting helps preserve more muscle/lean body mass (which is what we want).
However, when it comes to general weight loss, the overwhelming majority of evidence is most definitely not in favour of the insulin model of obesity having a significant metabolic advantage and the evidence is leaning towards caloric intake being the determining factor of weight loss.
Does this mean that we should oversimplify calories to help others lose weight, no, of course not and it’s never as simple as that.
The latter outcomes are especially evident when protein (which is the most thermogenic macronutrient) is controlled for.
What Will Break A Fast?
The following liquids do not break a fast:
• Black coffee
You can have as much as you want (but take it easy on the caffeine).
But wait, I thought you just said the coffee was okay in any amount?
Well, yes, but it depends on what you add in it. Black coffee is fine as the number of calories inside is negligible, but when you order a coffee from a cafe with added sugar and cream and chocolate sprinkles, then it becomes a problem.
Any coffee, tea or beverage which has sugar inside it is not appropriate during a fast under any circumstances. However, adding a quality source of fat to your coffee such as coconut oil, butter and/or MCT oil is fine.
Adding fat can actually be useful (not for weight loss), but if you’re making the transition into a ketogenic diet. The exogenous ketones from the dietary fat will fuel your brain with ketones while your body makes the transition into fat adaptation.
Adding fat is not necessary by any means and there is a limit. 1-2 coffees with added fat per day are most likely okay, but more than this is stretching it.
Think about it. If you drink 8 cups of coffee per day and each one has 120 calories worth of fat, then you’re consuming 960 calories which is the rough equivalent of two reasonably sized meals.
This is most definitely not traditional fasting and is considered a “fat fast”. You will still get many of the same benefits as a fast, just as you would on a ketogenic diet, but not to the same extent.
This one’s tricky.
Many artificial sweeteners are advertised as having zero calories and therefore this means they’re not going to spike insulin. Mark Sisson has written a detailed article covering whether artificial sweeteners elicit an insulin response.
The conclusion was that most don’t per se – some exacerbate the spike of insulin – but only when consumed with carbohydrates.
Artifical sweeteners are in a grey area. Generally, one or two is not going to do any harm, but I would avoid artificial sweeteners and diet sodas for other reasons such as the health of your gut microbiome. You don’t have to eliminate them, but there’s some convincing evidence that certain artificial sweeteners wreck havoc on your gut microbiota.
Does Coffee And Fat Prevent Autophagy From Occuring?
As I previously mentioned, intermittent fasting’s greatest benefit is not weight loss, it’s autophagy.
When you stay in a state of fasting ketosis for a prolonged period of time something called autophagy occurs. Autophagy roughly translates from Greek into “self-eating”.
Your body begins to eat itself. Sounds scary I know. Autophagy recycles waste from the body and repairs any oxidative stress (4).
Autophagy has anti-ageing properties and is also very important for muscular hypertrophy (growth).
There are some concerns about black coffee on its own and anything apart from water stopping autophagy, but I don’t think this is a realistic assumption.
There’s evidence showing that the ketogenic diet promotes macroautophagy in the brain (5).
In fact, the opposite is potentially true. Researchers speculate that the polyphenols inside the coffee help to promote autophagy (6). It’s important to mention that this is an animal-based study. However, the effects certainly didn’t indicate an inverse effect.
Alcohol is a grey zone. It depends on which source of alcohol you consume. Vodka, for example, is fasting-friendly, but most definitely not health friendly.
You can probably get away with a little bit of dry red wine on a ketogenic diet, but during a fast, this is pushing it. Alcohol is best to avoid in general, except for a little bit of red wine which has been shown to have some potential benefits for cardiovascular disease risk and the health of the brain. Remember, I’m not condoning it.
Alcohol is best to avoid in general as it can have adverse effects on important hormones such as testosterone. However, a moderate consumption of something like red wine isn’t all bad and has potential benefits for brain health and cardiovascular disease risk.
Black coffee, tea and water are fine.
Coffee/tea with small quantities of added fats such as cream, butter and MCT oil or a tiny bit of full-fat milk are okay in moderation (1-2 cups per day).
Artificial sweeteners are in a grey zone but are typically okay in moderation.
Anything with sugar is a no-no.
Black coffee, tea and quality fats shouldn’t prevent autophagy from occurring.
The dose makes the poison