When I first started this blog, I expected to write a lot about low carb eating, and some of the cool stuff that goes along with it, particularly cellular metabolism.
Since digging into other subjects, I haven’t spent too much time thinking about low carb eating, except to say that I still eat fairly low carb – probably less than 80 or 90g per day (full disclosure: I have plenty of cheat days, particularly on weekends, which is unhelpful for weight loss and maintenance).
When I first started eating low carb, it was a fantastic solution. I had been plateaued in my weight loss efforts (at the time, I weighed around 200 lbs), despite months of vigorous cardio and weight training exercise. Then I cut carbohydrate intake, and I dropped 10 pounds in a couple weeks, going as low as 188. My top adult weight was 235, and I had averaged between 210 and 215 for about 10 years.
I concluded a couple things about why low-carb eating is helpful (aside from the fact that it probably helps to “mix things up”, in terms of carbohydrate intake, from time to time), at least in the short term, for weight loss:
- It helps keep muscle and liver glycogen stores low (maybe 2/3 full), which stimulates increased fat metabolism (glycogen is just the storage form of glucose)
- Hormonal and Enzymatic effects were useful in contributing to fat metabolism
- Low insulin levels contribute to increased HSL and LPL activity in and on fat cells, which discourages fat accumulation, particularly in the areas where we’re inclined to gain fat, such as the belly (the saying goes that men accumulate fat above their waste, and women below).
- Various other hormonal effects, such as increased leptin expression can also contribute to increased fatty acid metabolism via similar mechanisms as the HSL and LPL mechanisms
In the beginning, low carb eating was so effective for me, I found I could stop exercising, and still maintain or lose weight.
Even now, when I go into full ketogenic mode, (where I’m consuming less than 40g of carbohydrates per day, and less than 10g of sugar, I find it’s still easy to drop about 1/2 pound a day up to a certain point (around 195lbs)…then it starts getting harder. But since going low carb, I’ve generally been in the 190-200 range.
Coming from a background where I put a lot of stock into calories-in-calories-out, and that one must create a caloric deficit to lose weight, it was a shock when I realized that I could eat a lot more of one particular type of macronutrient than another, and still manage to maintain or decrease weight; likewise, eating high-glycemic foods, in particular, very sugary foods, caused me to stagnate or increase weight, even when my caloric intake seemed low. This was a drag to realize because Mike and Ikes and Sour Patch Kids are my favorites.
Another anomaly I’ve only noticed lately is that I can eat fruit, and quite a bit of it, without gaining weight; I can also eat potatoes and rice – not a lot, but some – perhaps upwards to 70g per day while still decreasing weight. But if I eat sugar, particularly candy, my weight is almost certain to increase the next day. My threshold for sugar intake is somewhere between 30g and 90g per day, but I don’t have the exact number…my guess is 45-50g.
This anomaly got me wondering: do I really need to eat a low carb diet? Or is the problem really just sugar?
Recent toe-dipping into that question has rendered mixed result.
A couple days ago, I had a low-carb day (<40g) in combination with a high-glucose supper (12″ Subway Steak and Cheese with Mayo, Lettuce, Pickles, and Yellow peppers), and then a 28g candy bar, and my weight stayed stayed the same the next day.
Yesterday, I had a similar low carb day (again <40g), but had a supper with ground beef, potatoes, corn, and about 15g of a candy bar, and still kept the same weight.
One factor that may have played a role was a running injury I sustained the same day I ate the sub, so inflammation may be playing a role, where I otherwise might have decreased weight. I also have not been considering this question in terms of body fat or muscle mass, so I ultimately have no answer at all, in terms of healthy weight maintenance.
The golden hammer I had hoped for with low carbohydrate dieting remains elusive. I still think carbohydrate restriction, and even glucose restriction is a good thing (in particular for those individuals who are predisposed to easy fat accumulation or insulin resistance).
There are a few ideas about why I think high fat with carbohydrate limitation is a good thing:
- The brain is made up of about 60% fat. I think that gives a clue as to what percentage of our macronutrient intake should come from fat; frankly, it is quite difficult to consume 60% fat without limiting carbohydrate intake.
- During low energy demand, our fatty acid metabolism percentage is about 60%. I think this corroborates #1, and I arrive at the presumption that, in determining fat intake, a good starting point should be between 55 and 60%*
- *Note: Do this at your own risk. I’m not a doctor, so please take this statement with a grain of salt. I probably get about 60-65% of my daily energy from fat, although modern scientific consensus is that I should be dead by now with all this fat intake. Even liberal recommendations put fat intake between 30 and 40%.
- When we consume excess carbohydrates, our body does convert some of them to fat – this is called De Novo Lipogenesis. It’s evidently not a huge portion of our fat accumulation (5-10% as far as I can tell), but this phenomenon does happen when too many carbohydrates are consumed; overeating carbohydrates also raises LDL cholesterol level, because the fat produced in the liver is then sent into the bloodstream on (V)LDL lipoprotein molecules.
- The fact that we have about 300g of muscle glycogen + 100g of liver glycogen probably gives a clue. If we intake 0g of carbohydrates (or are fasted), our muscles will still keep a stock of about 200g of glycogen. The delta (100g) might give some insight into how much glucose we need per day…that’s pure speculation on my part, and frankly, it might not tell us much, considering that people can be healthy in a wide range of carbohydrate intake.
Caloric limitation does correlate to longevity. There’s probably something to be said for missing a meal now and then. I take the approach of maximizing the window that I don’t eat, while minimizing the window I do – this means that I start eating as late as I can in the morning, and I stop eating as early as I can. This seems to be a trend a lot of people are doing. I don’t know if it really helps or not, and I can think of reasons why it might not, in terms of weight loss, but I think it makes sense from other perspectives, such as increasing NRF-2 expression.
The Liver Factor
It’s pretty clear in my mind that the liver is critically important in overall health and weight maintenance. There are two manifestations that make this obvious:
- The huge increase in Non-Alcoholic Fatty Liver Disease in kids – 10% of American kids are affected by this, and the root cause is sugar – fructose is mainly metabolized in the liver, and the remaining glucose keeps glycogen reserves full, blood sugar high, and results in some amount of fat synthesis. The American Liver Foundation says this fatty liver disease “…is likely a combination of several factors, including a predisposing genetic background along with environmental triggers that allow for insulin resistance and accumulation of specific fats in the liver”. Of course NAFLD is exacerbated by certain genetic markers, but it’s fairly obvious that it is exacerbated by excess sugar intake, and correlates to subsequent (or perhaps pre-existing) insulin resistance.
- The fact that excess alcohol (another macronutrient that can only be metabolized in the liver) also causes fatty liver gives insight into the fact that the liver is ignored at our own peril.
I don’t have the silver bullet. I think low carb is the best way to make an obese nation less obese, and perhaps move it into the overweight category. I also think low carb eating helps with weight maintenance because you can stay full without spiking (and crashing) insulin levels.
There are three major pitfalls of high fat/low carb eating, as far as I can tell:
- It takes a long time (at least a couple weeks) for your body to adjust to it. You can counteract some of the negative outcomes by supplementing a lot of sodium, potassium, and magnesium, but it’s still sort of a process
- The bursts that glucose-based energy provides, especially in exercise type formats, is not as easy to get from fat.
- Because the default method to supply your brain with energy is with glucose (the liver supplies the brain with energy), the transition to non-glucose for this process can (and often does) result in “brain fog”, which is simply the inability to focus…this doesn’t seem quite “natural” to me, especially in light of the fact that some quick glucose fixes it immediately.
In my mind, #3 above is the reason why a ketogenic diet (< 30g of carbohydrates per day, along with limited protein) is not for everyone. But I still think non-ketogenic low-carb eating is probably a good thing, when coupled with limited sugar intake.
Favorite authors on the topic:
- Gary Taubes
- Peter Attia
- Robert Lustig
- Chris Kresser
- Chris Masterjohn
- Mark Sisson
- Abel James
- Nina Teicholz