I've been saying it all along!

Fasting is no more effective than creating a caloric deficit...

Ok, here is where I chime in with a MASSIVE "I told you so!"

I came across a recent study, shared by Menno Henselman, that proved what I've been saying for years... (click citation to access)

Vizthum, Diane, Sarah E. Katz, and Carly R. Pacanowski. "The impact of time restricted eating on appetite and disordered eating in adults: A mixed methods systematic review." Appetite 183 (2023): 106452.

Here are my thoughts on it...

Intermittent fasting gets a lot of hype these days.  Personally, I don’t get it.  Not eating? 

What is this? The Great Depression?

It’s like the new crossfit - you don’t have to wonder if someone does it because it’ll be the first thing they say when you meet them.

There is truly nothing more annoying than when someone bases their whole identity around a diet or training modality, but here we are in 2024 where everyone has to be part of a group and people think that inclusivity starts with exclusivity… but I digress.

Today we’re going to talk about intermittent fasting and why the hype is completely misguided and misappropriated….

Ah, I feel like I’m being pretty biased right now so I’m going to backpedal.  Yes, I have an opinion.  Yes, I think intermittent fasting should be reserved for people who’ve been kidnapped or held in off-the-grid penitentiaries.  But, also Yes, I have made my opinion based on the relevant data available to us on the subject and if anyone wants to refute me in the comments, I’d be happy to hear it, so pop a comment down below.

Back to it… Today, we’re going to talk about why intermittent fasting isn’t special.  Why the hype around it has been primarily used to push an agenda, sell products and mislead people into believing that weight loss can be as simple as not eating.

To do that, we’re going to run through the list of potential benefits by which intermittent fasting is purported to be a panacea of health and weight loss.  We’re going to look at the data and we’re going to give it a “Thumbs Up” or a “Thumbs Down”.  All the relevant citations will be available in the description, so you know I’m not totally full of shit like everyone else.  Plus, I love me some nerdy science.

Let’s get into it…

Next, we have to look at whether IF allows you to eat less calories and adhere to a larger caloric deficit and therefore create more fat loss.  This one makes a lot more sense in theory because if you’re spending less time per day eating, it stands to reason that you might end up consuming less calories.  Unfortunately, the optimism is slapped in the face by data.  The only way this could happen is if IF decreased your hunger signaling, which it doesn’t.  In fact, again there was no difference between groups when IF was compared to conventional dieting when it came to hunger signaling.

That all being said, I’ll bring in my own personal experience here, since I’ve both dieted to very low body fat levels and helped others to the same.  If you are following a strict diet and accountable to your macros or meal plan, delaying that first meal of the day can be very helpful in avoiding over consuming calories.  Practically speaking, hunger signaling for me and most of my clients seems to be lowest in the morning and if we delay that first meal a few hours, that means the spacing of our meals in the evening can be closer together.  Meaning when hunger is highest, we can just eat the foods we are supposed to be eating.  This only works if you have a ton of discipline because the longer you wait to eat that first meal, the easier it will be to over consume calories due to that high hunger signaling.

I’ve seen this time and time again with my lifestyle clients - they decide to try IF and it goes well for a week or two and then all of a sudden the flood gates open and they find it impossible to adhere to their nutritional targets.  Anecdotally, this is why I prefer a more steady meal frequency throughout the day for most clients.  Notice I said most, because some people thrive when they don’t have to eat in the morning and they report being incredibly energetic and productive.

Which brings me to the next question - does IF increase mental acuity, focus and energy?  Well, there is a growing body of research that in fact supports IF having a positive impact on cognitive function.  Here, there is a lot of mud in the water because we need to tease out whether the benefits of IF are due to factors outside of a caloric deficit.  Meaning that being in a moderate caloric deficit also increases mental acuity, focus and energy.  And that seems to be the consensus among top researchers in obesity - the calorie deficit is the magic and a calorie deficit is associated with most, if not all of the same potential benefits as IF.  But, for the sake of today and being fully transparent, I actually want to share a few really interesting things that happen when we abstain from eating.

First off, any change to the diet will affect the gut microbiome.  So, of course IF will cause some changes in your gut flora and those can have some really interesting effects.  First, it can cause a change in your neurotransmitters, since most of them are produced in the gut, to support a more positive mood.  

IF also increases BDNF, or brain derived neurotrophic factor, which increases neuroplasticity and could potentially positively impact neurological degeneration with age and has shown promise in off-setting the progression of certain brain diseases.

As someone who is very interested in increasing his productivity and living a long and vibrant life, I really want to believe there was some magic here, but unfortunately the research to date is spotty at best and overall, the calorie deficit seems to be where the true benefits lie.  Simply put, when we eat less, we are higher functioning… which kinda sucks because if you’re watching this video and following me, you probably want to eat big, get big and look like a superhero.  And if that’s the case, you know that when you eat more food, you feel and act like a lazy piece of shit and the moment you start dieting, or enter into a prep, you feel like a superstar.

So, does IF help improve energy levels and support cognitive function? Thumbs up!  But, it’s no better or worse than just being in a caloric deficit.

The last things we are going to look at here is cardiometabolic function.  Does IF improve your blood markers for Cardiovascular disease as compared to conventional dieting?  

I’ll be honest, this is one where I really wanted to find the magic of IF.  It makes sense on the surface.  You’re spending more time with lower blood glucose, which should positively impact insulin sensitivity, which is closely linked to most cardiometabolic issues, such as type 2 diabetes, high blood pressure, high cholesterol and high levels of inflammation.  Could the magic of IF be in the effects it can have on your blood work?

Again the research cannot tease out a difference between conventional dieting strategies and intermittent fasting.  Being in a caloric deficit does that too.  Trust me, I tried folks!

Being in a caloric deficit, by whatever means you achieve it, will lower insulin resistance, improve your cholesterol numbers, lower blood pressure and decrease inflammation.  The only way IF is superior is that these changes seem to happen faster.  How much faster?  That’ll depend on the person, but because abstaining from food is a very immediate intervention, it seems to cause these positive cardio metabolic effects quicker than simply reducing total caloric intake throughout the day.

So to me, IF gets a Thumbs Up for improving blood work for this reason alone.  For those of you watching who are enhanced and coming off a period of high androgen use, or you’re natural and just spent a period pushing calories up and carrying a significant amount of fat.  Starting your mini-cut, or health phase with an IF protocol could potentially bring your blood work back to baseline sooner than just starting to drop calories.  But again, you have to weigh the potential negatives that come with not eating…

And this is where my bias comes in big time - if the goal is to be as big and as strong as possible there are a few non-negotiables that IF really falls short on.

First, we need to preserve the quality of our training.  Abstaining from food can decrease our glycogen stores and potentially reduce the intensity of training.

Next, we want to ensure we’re maximizing muscle protein synthesis.  We have to remember that the research conducted does not take into account people who carry a lot of muscle tissue and train like animals.  Recovery from training is a 24hr process, so if we’re avoiding food for over half that time period, recovery will not be as effective and therefore the ability to adapt to training could potentially be negatively impacted.

Last, we need to make sure that we’re eating enough.  The people who are used in research for these studies are typically obese, metabolically compromised and do not have high caloric needs.  Shortening the feeding window makes it harder to eat enough protein, because it is highly satiating and puts additional stress on the digestive system by requiring a large volume of food to be processed in a shorter period.  IF just isn’t feasible for big strong people who have high caloric requirements and usually leads to some GI distress.

Now that we’ve got everything on the table, I think it’s safe to say that the evidence is spotty at best when it comes to supporting any positive benefits of intermittent fasting outside of simply allowing you to achieve a caloric deficit.

That is where the magic lies.  Eating less calories will allow you to lose weight, improve cognition and improve your blood work.  Doesn’t matter how you get there.

When you layer on the specific needs of someone who is wanting to build a muscular physique with high level performance capacity, IF does fall short in a number of key areas.

IF is not a quick fix, but it does have some practical benefits at the very tail end of a deep dieting phase, or if you need to get your blood work in order as quickly as possible.  So, it’s not totally useless.

The key here is adherence.  If you find that shortening your feeding window helps you adhere to the diet more easily, by all means you’re not going to be shooting yourself in the foot for performance, but there may be some concessions you’ll need to accept.

For me, it’s something I’ll rarely advise a client to do outside of rare circumstances where they either prefer it, or they’re coming to me with some pretty serious health concerns.

So, what do you think? 

Keep Raising the Bar,

Paul Oneid MS, MS, CSCS