“…But Tony the Tiger tells us that breakfast is the most important meal of the day! Grrrrrreat!”
And Tony the Tiger would NEVER lie…
This adage about breakfast has become commonplace that it’s readily and unquestionably accepted as fact:
“Want to lose weight? Make sure you start off with a healthy breakfast, so you can get that metabolism firing first thing in the morning! “Eat breakfast like a king, lunch like a prince, and dinner like a pauper.”
“Want to lose more weight? Make sure you eat six small meals throughout the day so your metabolism stays operating at maximum capacity all day long.”
There are even studies that show those that eat earlier in the day lose more weight than those who ate later in the day or skipped a meal.
So, eat breakfast to lose weight and obtain optimal health.
Maybe there’s way more to the story: what if there’s science and research that shows SKIPPING BREAKFAST (the horror! blasphemy!) is can help with optimum human performance, mental and physical health improvement, maximum muscle retention, and body fat loss?
After firmly being on “Team Breakfast” for 28 years of my life, I’ve skipped breakfast for the past 3.5 years and will most likely never go back!
I want to share with you a concept about skipping breakfast (and other meals), and how your health can benefit as a result.
I’m typing this from a secure location, just in case Tony the Tiger, The Trix Rabbit, and Toucan Sam come to beat me up.
After all, I’m going to rain on their breakfast parade with science today.
This is a topic that is controversial (which is funny – you’re just skipping a meal) as it turns a LOT of conventional wisdom on its head. This is why this article is filled with more sources and citations than the normal Nerd Fitness article.
What is intermittent fasting?
Intermittent fasting is not a diet, but rather a dieting pattern.
In simpler terms: it’s making a conscious decision to skip certain meals on purpose.
By fasting and then feasting on purpose, intermittent fasting generally means that you consume your calories during a specific window of the day, and choose not to eat food for a larger window of time.
There are a few different ways to take advantage of intermittent fasting, which I learned about back in the day from Martin over at LeanGains, a resource specifically built around fasting and strength training:
What it is: Fasting for 16 hours and then only eating within a specific 8-hour window. For example, only eating from noon-8 PM, essentially skipping breakfast.
Some people only eat in a 6-hour window, or even a 4-hour window. This is “feasting” and “fasting” parts of your days and the most common form of Intermittent Fasting. It’s also my preferred method (3 years running).
Two examples: The top means you are skipping breakfast, the bottom means you are skipping dinner each day:
You can adjust this window to make it work for your life:
- If you start eating at: 7AM, stop eating and start fasting at 3pm
- If you start eating at: 11AM, stop eating and start fasting at 7pm
- If you start eating at: 2PM, stop eating and start fasting at 10pm
- If you start eating at: 6PM, stop eating and start fasting at 2AM.
24 HOUR PROTOCOL
Skipping two meals one day, where you are taking 24 hours off from eating. For example, eating on a normal schedule (finishing dinner at 8PM) and then not eating again until 8PM the following day.
So you would eat your normal 3 meals per day, and then occasionally pick a day to skip breakfast and lunch the next day.
If you can only do an 18 hour fast, or a 20 hour fast, or a 22 hour fast – that’s okay! Adjust with different time frames and see how your body responds.
Two examples: skipping breakfast and lunch one day of the week, and then another where you skip lunch and dinner one day, two days in a week.
Those are the two most popular intermittent fasting protocols, and the two we’ll be focusing on, though there are many variations of both that you can modify for yourself.
Some people eat in a 4 hour window, others do 6 or 8. Some people do 20 hour fasts or 24 hour fasts. You’ll need to experiment with them, adjust them to work for your lifestyle and goals, and see how your body responds.
Let’s first get into the science here behind Intermittent Fasting and why you should consider it!
How does intermittent fasting work?
Now, you might be thinking: “okay, so by skipping a meal, I will eat less than I normally eat on average (2 meals instead of 3), and thus I will lose weight, right?”
Yes, by cutting out an entire meal each day, you are consuming fewer calories per week – even if your two meals per day are slightly bigger than before. Overall, you’re still consuming fewer calories per day. This is highlighted in a recent JAMA study[b] in which both calorie restricted dieters and intermittent fasters lost similar amounts of weight over a year period.
That doesn’t tell the FULL story, as we already know that not all calories are created equal, and that the timing of meals can also influence how your body reacts.
Intermittent Fasting can also help because your body operates differently when “feasting” compared to when “fasting”:
When you eat a meal, your body spends a few hours processing that food, burning what it can from what you just consumed. Because it has all of this readily-available, easy to burn energy (thanks to the food you ate), your body will choose to use that as energy rather than the fat you have stored. This is especially true if you just consumed carbohydrates/sugar, as your body prefers to burn sugar as energy before any other source.
During the “fasted state” (the hours in which your body is not consuming or digesting any food) your body doesn’t have a recently consumed meal to use as energy, so it is more likely to pull from the fat stored in your body as it’s the only energy source readily available.
Burning fat = win.
The same goes for working out in a “fasted” state. Without a ready supply of glucose and glycogen to pull from (which has been depleted over the course of your fasted state, and hasn’t yet been replenished with a pre-workout meal), your body is forced to adapt and pull from the only source of energy available to it: the fat stored in your cells.
Why does this work? Our bodies react to energy consumption (eating food) with insulin production. The more sensitive your body is to insulin, the more likely you’ll be to use the food you consume efficiently, and your body is most sensitive to insulin following a period of fasting .
Next: Your glycogen (a starch stored in your muscles and liver that your body can burn as fuel when necessary) is depleted during sleep (aka during fasting), and will be depleted even further during training, which can lead to increased insulin sensitivity.
This means that a meal following your workout will be stored most efficiently.
During that period, the food you consumed will be used in a few ways: converted to glycogen and stored up in your muscles or burned as energy immediately to help with the recovery process, with minimal amounts stored as fat.
Compare this to a regular day (no intermittent fasting): With insulin sensitivity at normal levels, the carbs and foods consumed will see full glycogen stores and enough glucose in the bloodstream, and thus be more likely to get stored as fat.
Not only that, but growth hormone is increased during fasted states (both during sleep and after a period of fasting). Combine this increased growth hormone secretion:, the decrease in insulin production (and thus increase in insulin sensitivity ), and you’re essentially priming your body for muscle growth and fat loss with intermittent fasting.
The less science-y version: Intermittent fasting can help teach your body to use the food it consumes more efficiently, and your body can learn to burn fat as fuel when you deprive it of new calories to constantly pull from (if you eat all day long).
TL/DR: For many different physiological reasons, fasting can help promote weight loss and muscle building when done properly.
Why intermittent fasting?
Now that we’re through a lot of the science stuff, let’s get into the reality of situation: why should you consider Intermittent Fasting?
Because it can work for your goals. Although we know that not all calories are created equal, caloric restriction plays a central role in weight loss. When you fast, you are also making it easier to restrict your total caloric intake over the course of the week, which can lead to consistent weight loss and maintenance.
Because it simplifies your day. Rather than having to prepare, pack, eat, and time your meals every 2-3 hours, you simply skip a meal or two and only worry about eating food in your eating window. It’s one less decision you have to make every day. It could allow you to enjoy bigger portioned meals (thus making your tastebuds and stomach satiated) and STILL eat fewer calories on average.
It requires less time (and potentially less money). Rather than having to prepare or purchase three to six meals a day, you only need to prepare two meals. Instead of stopping what you’re doing six times a day to eat, you simply only have to stop to eat twice. Rather than having to do the dishes six times, you only have to do them twice. Rather than having to purchase six meals a day, you only need to purchase two.
It promotes stronger insulin sensitivity and increased growth hormone secretion, two keys for weight loss and muscle gain. Intermittent fasting helps you create a double whammy for weight loss and building a solid physique.
It can level up your brain, including positively counteracting conditions like Parkinson’s, Alzheimer’s, and dementia. As explained here in this TEDx talk by Mark Mattson, Professor at Johns Hopkins University and Chief of the Laboratory of Neurosciences at the National Institute on Aging fasting is grounded in serious research and more studies are coming out showing the benefits:
Plus Wolverine does it:
Can I build muscle and gain weight while intermittent fasting?
You’re damn right you can!
In fact, I have been intermittent fasting for the past three years while building muscle and decreasing my body fat percentage:
I still eat roughly the same number of calories I was consuming before, but instead of eating all damn day long, I condense all of my calorie consumption into an eight hour window.
- 11 AM Work out with heavy strength training in a fasted state.
- 12 PM Immediately consume 1/2 of my calories for the day (a regular whole-food meal, followed by a calorie-dense homemade shake.)
- 7 PM Consume the second portion of my calories for the day in a big dinner.
- 8 PM – 12 PM the next day: Fast for 16 hours.
In a different method, my friend Nate Green packed on a crazy amount of muscle while fasting for a full 24 hours on Sundays – so it is possible. 
I’m not kidding when I say this has revolutionized how I look at muscle building and fat loss.
Ultimately, this method flies in the face of the typical “bulk and cut” techniques of overeating to build muscle (along with adding a lot of fat) before cutting calories to lose fat (along with some muscle) and settling down at a higher weight.
I prefer this method to the bulk-and-cut technique for a few reasons:
- There’s far less of a crazy swing to your weight. If you are putting on 30 pounds and then cutting 25 to gain 5 lbs of muscle, your body is going through drastic swings of body mass. Your clothes will fit differently, you’ll have different levels of definition, and your body will wonder what the hell is going on.
- You’re consuming less food and thus spending less money. Rather than overeating to put on 1 pound of muscle and 4 pounds of fat in a week or two, you’re aiming to eat exactly enough to put on 1 pound of muscle without adding much fat on top of it. Yeah, it’s a delicate balance, but there’s far less swing involved. You are just slowly, steadily, and consistently building muscle and strength over many months.
- There’s never a need to get “vacation-ready”: we all want to look good naked, right? When you are just adding muscle, you don’t need to worry about getting your body ready before by drastically altering your diet (going on a miserable crash diet for a month). 
- You can make small adjustments and stay on target. Keep your body fat percentage low, build strength and muscle, and if you happen to notice your body fat creeping up, cut back on the carbs. Within two weeks you should be back at your preferred body fat percentage and can continue the muscle building process.
A note on BCAA consumption. Martin from LeanGains  recommends consuming Branched Chain Amino Acids (BCAA’s) as a supplement with regards to fasted training to aid your muscles through your workout.
Personally, I used BCAAs for about 6-8 months during my initial start with fasted training (consuming them before training), though haven’t used them in the past 2+ years. I did NOT notice any adverse affects to not taking them with regards to my performance. Your value may vary!
We get more questions about Intermittent Fasting than any other topic at Nerd Fitness. People who are looking for the key to their weight loss struggles or who have heard about it from a celebrity or friend or on the news and want to know what it’s all about.
Remember that Intermittent Fasting is a piece of the puzzle. If you have been struggling with weight loss all your life, Intermittent Fasting can HELP, but it needs to be part of a well balanced approach that works for your lifestyle, body type, lifestyle, experience and goals.
Does intermittent fasting have different effects on men and women?
The quick answer is: “yes, Intermittent Fasting can affect men and women differently.” Anecdotally, I know many women that swear by Intermittent Fasting, while others have had adverse effects. Let’s dig into the science and studies.
A recent PubMed summary concluded that “fasting can be prescribed as a safe medical intervention as well as a lifestyle regimen which can improve women’s health in many folds .
Now, in that extract, many of the studies cited are focused on specifically calorie restriction (and not just fasting), and they also say that “future studies should address this gap by designing medically supervised fasting techniques to extract better evidence.”
Digging into the PubMed Archives brought me to the following conclusions [a]:
One small study (with 8 men and 8 women, all non-obese) resulted in the following: “Glucose response to a meal was slightly impaired in women after 3 weeks of treatment, but insulin response was unchanged. Men had no change in glucose response and a significant reduction in insulin response.”
Another small study (8 women) studied the effects on their menstrual cycles after a 72 hour fast – which is significantly longer than any fast recommended in this article: “in spite of profound metabolic changes, a 72-hour fast during the follicular phase does not affect the menstrual cycle of normal cycling women.” .
Yet another study tracked 11 women with 72 hour fasts (again, longer than we’d recommend) and it found that “Fasting in women elicited expected metabolic responses – included increased cortisol (a stress hormone) – and apparently advanced the central circadian clock (which can throw off sleeping patterns). .
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.
There are also a series of articles out there that dig into the potential reproductive health issues, stress challenges, induction of early-menopause  associated with fasting (and calorie restriction) for women.
Precision Nutrition recommends not attempting Intermittent Fasting as a woman if:
- you’re pregnant
- you have a history of disordered eating
- you are chronically stressed
- you don’t sleep well
- you’re new to diet and exercise
The challenge associated with all of this is that there aren’t enough long-term studies, with large enough sample sizes, specifically targeting female humans, with relation to the different types of Intermittent Fasting.
ALL OF THIS TO SAY: It does appear that men and women will have different experiences with intermittent fasting; we’re all unique snowflakes (yep, especially you), and your body will be affected by intermittent fasting differently than the person next to you.
There is enough evidence as cited in the articles and studies above that would give me pause to recommend Intermittent Fasting for women, especially if you are considering getting pregnant in the near term.
If you are looking to attempt intermittent fasting for weight loss reasons, my research has shown me that Intermittent Fasting could be less effective for women than men with regards to weight loss, and thus you would be wise to keep your efforts elsewhere:
- Focusing on the total calories and quality of your food (here’s how to eat better).
- Start exercising regularly!
- Make sure you are getting enough sleep.
Now, if you’ve read the above warnings, you are still curious about Intermittent Fasting, and you want to give it a try as a female, that is your choice! You know your body best.
So, get blood work done, speak with your doctor and get a check-up. Give intermittent fasting a shot, track your results, and see how your body/blood work changes as a result of Intermittent Fasting and decide if it’s right for you.
Your milage may vary, so speak with a doctor or find a doctor versed in intermittent fasting protocols and treat it like an experiment on yourself!
Special thanks to Nerd Fitness and Steve Kamb for sharing their insights with us!
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