Fasting is one of the easiest ways to restore your metabolic health. But that doesn’t mean there’s a one-size-fits all approach. The last thing I want is for you to burn out and give up — or in a worst-case scenario, accidentally harm yourself.
If you want to get more comfortable with fasting, start by designing a completely customized regimen. This will help you reap the benefits at any stage of your health journey, whether you’re optimizing specific eating windows or trying to manage a condition like type 2 diabetes.
First, a word on fasting
If you follow me on X, you know I’m a huge fan of fasting. It can help with food addiction, weight loss, and blood sugar management, ultimately reducing your risks for cardiovascular disease.
Science proves fasting can improve your metabolic health with:
- Reduced LDL cholesterol and triglycerides
- Autophagy (removing damaged cells)
- Increased longevity
- Better mood
That’s not to say you can’t do fasting incorrectly — taking the wrong approach could harm your metabolic health. You could imbalance your hormones, lose large amounts of muscle, and potentially develop gallstones that require surgery to remove.
The best solution, then, isn’t copying someone else’s fasting approach. It’s listening to your body and building a customized plan.
Here’s how.
Constructing a long-term plan for metabolically healthy fasting
If you want to start fasting both healthily and sustainably, you’ll need to establish:
An eating window
Eating windows are periods of time where you’re ‘allowed’ to eat. There are three major types:
- Intermittent fasting (IF). This is typically 12 to 16 hours, although some people prefer intermittent fasting as long as 18 or 20 hours (up to 23 hours if they’re eating one meal per day)
- Extended fasting. Usually two to seven days. This offers significant health benefits when done sporadically, but isn’t ideal for first-time fasters.
- Prolonged fasting. Up to two weeks or longer. Not recommended for most healthy individuals, but may have merit for those who are extremely overweight or have significant or time-sensitive health issues.
If you’ve never tried fasting, intermittent fasting is the best place to start. Don’t be intimidated by the 12-hour timeline: if you normally sleep eight hours per night, you’ll be automatically fasting at least eight hours per day. Tacking on an extra four hours (two in the morning and two at night) will give you a tighter eating window while spacing three meals around four hours apart.
Some people prefer to eat just two meals a day, or one meal a day (OMAD) to accommodate longer fasting windows. You’ll hear different things about the benefits of fasting longer, but at the end of the day, I just want you to get started.
It might take your body a few days to adjust, so expect the occasional hunger pang in between eating sessions. You might also feel a little out of sorts in the beginning. This is normal, especially as you become fat adapted. It will get better and go away over time.
Give yourself grace, of course, but don’t be afraid to push the envelope. Be sure to eat enough food within your window, but do your best to avoid eating late at night.
As you get more comfortable with your specific eating window, try upping the ante by an hour or two once in a while. If you can get down to an eight-hour window or a six-hour eating window, you’ll see faster results more frequently.
A proper human diet
You can technically consume whatever you want within your eating window. However, the most successful long-term fasters follow a ‘proper human diet.’ This means a diet composed of whole, real foods with no processed foods, seed oils, or added sugar content.
Fasting diets are also typically low-carb diets — these can help you reach ketosis faster and avoid blood sugar spikes that could make you feel groggy or tired. Other eating patterns like vegetarian, vegan, and Mediterranean can work. Just keep in mind you’ll feel fuller longer with a heavier emphasis on red meat, eggs, and nuts and seeds.
There are many different eating styles on the ‘proper human diet’ spectrum:
- Keto/ketovore
- Low-carb
- Carnivore
- Lion
Of course, following a proper human diet includes proper hydration, particularly with electrolytes to keep sodium levels high. If you don’t want to buy pre-made electrolytes, you can always make your own. Lemon juice, salt, and magnesium powder are a fairly common DIY.
No matter how long your eating window is, plan to eat enough to keep you full. Counting calories isn’t all that important if you’re already restricting your eating window.
Some pointers:
- Before you fast, eat plenty of protein and fat. Avoid high-carb foods or added sugar. If you’re not yet fat adapted, focus on whole, real carbs from vegetables and milk. This will make your transition much more comfortable and sustainable.
- At the end of your fast, eat something light before your main meal. This will help you prevent unwanted blood sugar spikes. Boiled eggs, bone broth, and avocado are popular since they’re low in carbs and high in protein/fat.
- If you start feeling dizzy, nauseous, or faint, immediately break your fast and set up a visit with your doctor. There’s a good chance you need more fuel before or after fasting, or you need to shrink your window to avoid bottoming out with hypoglycemia or hypotension.
Regular lab work
The best way to know how your body reacts to fasting is to track its responses over time. This is the magic of biannual blood work: you can get accurate readings of your blood sugar, fasting glucose, and vitamin/mineral levels.
I recommend getting at least three blood labs regularly:
- Complete metabolic panel (CMP)
- Complete blood count (CBC)
- Advanced Lipid Testing (triglycerides and HDL ratio)
You can also consider a continuous glucose monitor, which helps keep an eye on blood sugar both during and after eating windows. For example, you might notice your blood sugar is dipping too low during fasting periods, or notice that specific foods like honey or fruit make it difficult to get back into ketosis.
Whether you opt for a CGM, bloodwork, or both, you’ll have more visibility on how your body reacts to fasting. That way, it’s much easier to track your progress over time, make tweaks and changes, and celebrate when reaching hard-fought goals.
Successfully implementing your fasting routine
You’ll hear all sorts of rhetoric about what is (and what isn’t) the best approach to fasting. In my opinion, there’s no such thing as ‘the best’ — only the method that makes sense for your body.
Start small, be vigilant, and track your numbers as often as you can. If you feel your body is ready for more, slowly increase your fasting duration.
I also realize we’ve just barely scratched the surface. If you’ve tried fasting before, all this might feel very overwhelming. If you’re looking for a more entry-level guide to fasting, you’re welcome to explore my introduction to fasting course.
