My take on low carb diets has changed: this article covers why low carb may be best for weight loss and longevity, especially for the over 40s.
22-Oct 2016, by Lee Sandwith
For a long time, my position on low carb diets has been pretty strong; I was never a fan and thought they were a bit pointless.
For the best part of the last 10 years – with the exception of the last 9 months or so – I’ve pretty much stuck to the same diet. The principles are simple: consume less calories than you burn, get a good balance of macronutrients.
Specifically, from a macro perspective, I’ve always been an advocate of a 40-20-20 ratio; that is, 40% protein, 20% carbs and 20% fat.
It worked a treat.
At my peak, i.e. when I was kinda obsessed with getting to single digit body fat percentage, the leanest I got to was around 8%. That was pretty tough for me but it was done using the above principles.
Carbs as the body’s main energy source
The foundation of this weight loss approach is that the most important macro to get right is protein as insufficient amounts has the potential to cause muscle loss while the body is in a calorie deficit.
Carbs are needed for energy and the best choice is always healthy, complex carbs as they break down slowly keeping hunger at bay for longer, and they have a less negative effect on blood sugar than simple carbs.
Fat should be minimised as it’s the most calorie dense macro and can easily push you calories over your daily target.
Saturated fat is extremely bad and should be avoided.
This is what most people understand and it’s what is taught in most nutrition courses, and this is broadly the approach that I used to advocate.
A quick search on Google will pull up lots of articles to support these claims so I won’t bother adding any references.
Don’t get me wrong, it’s works. I’m living proof of that, however, it’s not a perfect model.
It’s definitely not the only way to lose weight and it’s probably not the best approach in terms of promoting longevity.
This is the main shift in my understanding of human nutrition, specifically in relation to longevity. It’s a fundamental change which has caused some anxiety about this whole ingfit thing and had me leaning towards removing my website altogether.
However, I’m acutely aware that most people in my circle are still at nutrition ground zero. Even some of the most brilliant individuals still get super confused and frustrated at how complex it all is.
That’s a result of a couple of things. First, there’s so much information out there, much of it conflicting, that people just lose hope; and second, in this busy world we find ourselves in, people just don’t have time.
That’s understandable and something I think I can do something about. I invest a lot of my spare time into learning about these things so my plan is to pull out the important stuff, simplify things and share actionable steps which you can try out in your day to day life.
So what are carbohydrates?
Carbohydrates are organic compounds made up of carbon, hydrogen and oxygen atoms (1).
Technically they are classified as monosaccharides, disaccharides or polysaccharides depending on whether they comprise one, two or multiple sugar molecules, however, in nutrition terms, it is more common to classify carbohydrates as either simple or complex.
Examples of simple carbohydrates are glucose, fructose and galactose, examples of more complex carbohydrates are starch, glycogen and cellulose (2).
Once consumed, carbs are broken down into smaller units of sugar by the stomach and small intestine. These smaller units of sugar are then absorbed into the bloodstream and transported to the liver where they are further broken down into glucose.
Via the bloodstream, glucose is then transported to tissues and organs, including the brain, where it is used for energy throughout the day. Any energy which is not required is stored in the liver and muscles as glycogen (3).
Carbohydrates are sugars, defined as either simple or complex depending on the complexity of the molecule.
Note, this is a very high level explanation which is tailored to the theme of this article; for more in depth view you could check out out this article from BuiltLean or this one from Authority Nutrition. Both articles are very well written and come from trusted sources.
Are carbohydrates the body’s preferred energy source?
For a long time, my understanding was that carbohydrate is the body’s preferred energy source. That is, the body uses protein to build and repair tissues, it uses carbs for immediate energy needs and it prefers to use dietary fat last as it’s the most calorie dense and the most valuable macronutrient.
I also thought that the body always chooses to burn muscle before body fat given that fat is more calorie dense and that’s the reason that high levels of protein is required, that is, to avoid muscle catabolism.
After what I’ve learned recently, I’m pretty confident that this is not true, especially when ketosis comes into the picture (more on this later).
Touching on these ideas even at the very highest level raises questions about a bunch of other topics, such as simple carbs versus complex carbs, glucose, insulin sensitivity and insulin resistance, fasting, the gut microbiome, and even conditions such as diabetes and cancer.
I’ve covered most of these topics in previous articles but I’m planning to revisit some of them as, when it comes to longevity, I believe that it’s extremely important to understand some of the mechanisms, especially insulin sensitivity.
To circle back, it has recently come to my attention that carbs may not the body’s preferred energy source and that there’s a good chance that the body, and specifically the brain, prefers ketones, or ‘ketone bodies’, over glucose for energy.
For me, this is an entirely new concept. I’m not saying that it’s 100% true, I’m saying that it ‘may’ be the case. There are opinions on both side of the fence so if you want to be completely objective about it then the jury is still out, however, there’s a bunch of emerging research to support the case.
Personally, I will be keeping an open mind, however, it’s actually something of a moot point as the key thing to consider is that the body doesn’t need glucose as the main source of energy, it can definitely use ketones too.
Blood glucose never depletes completely but it can be significantly reduced if the body starts to use ketone bodies. From a longevity perspective, optimising blood glucose levels is most probably a very good thing.
How wrong can you get it?
Accepting that glucose is not the body’s only energy source changes everything. At least, it changed everything for me and renders a couple of sections in my eBook inaccurate.
I’ve always been one to advise that carbs are essential in the diet and I’ve always promoted a fair balance between carbs, protein and fat.
Further, I’ve always advocated the typical, western approach to weight loss in that a low fat approach is best, with specific emphasis on taking care to avoid saturated fat as it is super unhealthy and leads to terrible things like heart disease.
Although this approach still works, I was wrong to be so closed minded about considering a low carb diet. However, after much deliberation, given that it’s what is advocated in pretty much all of the literature, courses and governmental health guidelines pretty much across the world, I’ve reached the conclusion that this is a forgivable mistake.
Getting this so wrong is what almost made me take down my website but it’s also the thing that has encouraged me to keep going.
Why low carb diets don’t suck, probably
People tend to have very strong opinions about low carb diets and you can easily find as many articles supporting low carb diets as those opposing them.
Personally, I am still not completely over the fence but I’ve learned enough about the potential upsides of restricting carbs for my attention to be well and truly caught.
This is where it’s important to think about what you’re trying to optimise for, for example, are you looking to lose weight, build muscle or try to stay alive and well for as long as humanly possible.
Personally, I’m interested in all of these things but I’ve seen enough evidence to suggest that a low carb diet may be the best approach, especially for those of us lucky enough to have breached the milestone age of 40.
So, to answer the exam question, low carb diets probably don’t suck because restricting carbs may be the best way to manage weight AND promote longevity, especially for the over 40s.
Now that we have dealt with that question it’s time to move onto the topic which is quickly becoming my new obsession: The Ketogenic Diet.