A 2018 review of intermittent fasting in obese people showed that reducing calorie intake one to six days per week over at least 12 weeks was effective for reducing body weight on an average of 7 kilograms (15 lb); the results were not different from a simple calorie restricted diet, and the clinical trials reviewed were run mostly on middle-aged women from the US and the UK, limiting interpretation of the results.[25] Intermittent fasting has not been studied in children, the elderly, or underweight people, and could be harmful in these populations.[25][26]
I was very curious about this, so I asked the opinion of metabolic expert Dr. Deborah Wexler, Director of the Massachusetts General Hospital Diabetes Center and associate professor at Harvard Medical School. Here is what she told me. “There is evidence to suggest that the circadian rhythm fasting approach, where meals are restricted to an eight to 10-hour period of the daytime, is effective,” she confirmed, though generally she recommends that people “use an eating approach that works for them and is sustainable to them.”
With this information in hand, you should know exactly how to schedule meals when starting an intermittent fasting plan. And while it might seem complicated at first, once you get into the habit of fasting, it will feel like second nature and fit pretty seamlessly into your days. Just remember to always start slow and gradually work up to more advanced plans.
Listen to your body during workouts. If you get light headed, make sure you are consuming enough water. If you notice a significant drop in performance, make sure you are eating enough calories (especially fats and protein) during your feasting window. And if you feel severely “off,” pause your workout. Give yourself permission to EASE into intermittent fasting and fasted workouts. This is especially true if you are an endurance athlete.
Nuts and seeds make great snacks that are high-fat and can be eaten around 2:30 p.m. Soaking these beforehand can help neutralize naturally occurring enzymes like phytates that can contribute to digestive problems. Eat dinner around 5:30 p.m., and just like the 8-to-6 window plan, a dinner with some sort of wild-caught fish or other clean protein source with vegetables is a great option.
Fill your plate with plenty of healthy fats, such as coconut oil, avocados, olive oil, ghee and grass-fed butter as well as moderate amounts of protein foods like grass-fed meat, free-range poultry, fatty fish and eggs. Non-starchy vegetables, fresh herbs, nuts, seeds and healthy beverages like water, bone broth and green tea can all be enjoyed as well.
Although some of the intermittent fasting methods online seem more intense than others (some can last upwards of 48 hours), the beauty of intermittent fasting is that you get to choose and experiment with how long you fast. This not only allows you to determine how intermittent fasting can fit in within your lifestyle, but to discover the fasting sweet spot that helps you feel best physically.
Another big concern of mine, but it turns out this fear was unfounded. We’ve been told by the supplement industry that we need to consume 30 g of protein every few hours, as that’s the most amount of protein our body can process at a time. Along with that, we’ve been told that if we don’t eat protein every few hours, our body’s muscle will start to break down to be burned as energy.
In practice, however, I would be concerned with eating enough. Based on my experience, teaching yourself to consistently eat more is one of the harder parts of intermittent fasting. You might be able to feast for a meal, but learning to do so every day of the week takes a little bit of planning, a lot of cooking, and consistent eating. The end result is that most people who try intermittent fasting end up losing some weight because the size of their meals remains similar even though a few meals are being cut out each week.
Surprisingly, since I've started intermittent fasting I've increased muscle mass (up 10 pounds from 205 to 215), decreased body fat (down 3% from 14% to 11%), increased explosiveness (set a personal best with a clean and jerk of 253 pounds a few months back), and decreased the amount of time I've spent training (down from 7.5 hours per week to 2.5 hours per week).
With methods like this, when the contact time between the water and the grounds is longer, a coarser grind is essential. If the grind is too fine, the grounds can get stuck in the filter or even get through the filter causing problems. It can make it harder to press down on the plunger and your coffee can end up with grinds in it. Worst of all, the finer grind means the coffee is left in contact with the water for too long, causing a bitter brew.

On the flip side of that, eating keto can make your periods of fasting more manageable. For example, someone who is eating a diet higher in carbs will likely have more discomfort with intermittent fasting as the body constantly switches between glucose for fuel and ketones for fuel. By continuing to eat keto even during feeding periods, you can keep your body constantly running on ketones.
Put a coffee filter or your cheesecloth (you can even use a paper towel if you don’t have a coffee filter/cheesecloth) into the mesh strainer and place it over another glass container. Gently pour the filtered coffee through the filter and let it slowly drip into the glass container below. If the filter fills up, just wait and let it drip naturally (this could take up to 10 minutes).
So very interesting, I was captivated reading your results—thank you! I would also love to see added to this research the keto effect of just water over those 120 minutes, and then the keto effect of adding collagen powder to your coffee. So appreciative of all that wincing-sticking-your-fingers that you both endured to help give us clarity in what goes on with our ketones and glucose when drinking our coffees with different add-ins. Great read!
Intermittent fasting, commonly referred to as IF, has become all the rage lately, and it doesn't look like the trend is going away anytime soon. The practice of intermittent fasting, or time-restricted feeding, is when a person limits the period of time in which they consume calories down to a limited number of hours. So for example, I practice IF with an eight-hour eating window, which means that I will only eat between the hours of 12 p.m. and 8 p.m.
Cons: Even though it’s nice to eat a few snacks rather than go without any food for 20-plus hours, the guidelines for what you need to eat (and when) can be hard to follow long-term. The strict schedule and meal plan may also interfere with social gatherings. Additionally, eating one main meal at night — while following strict guidelines of what to eat, and in what order — can be tough. It’s especially hard for those who prefer not to eat large meals late in the day.

Those studies above, in working with small sample sizes, and different types of fasting than recommended here, would lead me to believe that fasting affects men and women differently, and that many of the weight loss benefits associated with intermittent fasting (that affect insulin and glucose responses) work positively for men and negatively for women.
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