I currently eat around 150 grams of carbohydrates a day. I wouldn’t class this as a LCHF diet, however when I look at my macronutrient breakdown, the majority of my calories still seem to come from fats. Typically about 60 % of my calories comes from fats, and 20 % from carbohydrates and 20% from Proteins.
I’m aware that on a very Low carbohydrate diet, the body changes the way in which it metabolises fats. What I’m unsure of is how it uses fats if you’re eating say 150 grams of carbohydrates a day. Is it still possible to simply for the body to use fats as energy in these cases?
Hi Donman90, I do know a bit about the topic you are asking about. Every human can metabolize fats, and every human does use fats for energy almost every day. The two times this is most common are after fasting and during long, intense exercise.
Most people will have trace amounts of ketones when they wake in the morning and have fasted for more than eight hours. This indicates a normal metabolic process: some dietary or stored fat has been “burned” for energy because it’s been a long time since carbohydrates were consumed.
When athletes (or even amateurs) exercise intensely, they sometimes hit “the wall” or “bonk.” This is when your body has used all the glycogen (carbohydrate joined with water for storage in muscle tissue) available in the muscles to fuel the exercise. After glycogen is depleted, the body shifts to burning fat for fuel. If you were to test for ketones after a long run, swim, or cycling outing you’d like test trace or small if you hit that “wall.”
So, the 150 g per day of carbs may or may not be “low carb” as far as your body is concerned, depending on how much energy you actually expend during the day. As a reference, I consume between 50-80g of carbohydrate per day in a 2,300 calorie per day diet. Over the last week, that averaged out to 69g of carbs per day, with 29g of dietary fiber per day. I exercise a lot, although this winter I’ve only been working out hard three times a week, but I also walk or ride my bike almost every day around town. I’m a big guy (~180 lb) with low body fat, and I am almost constantly in a state of “ketosis” (i.e., fat-burning metabolism). When I do eat carbohydrate, it usually goes to replenishing muscle glycogen, and my body generally runs off that fat metabolic pathway you’re asking about.
So yes, the body does use fats when it’s starving (after fasting for even short times) or in those who exercise a lot. It really comes down to an individual and how much energy they consume and expend: because I eat fairly low-carb and exercise a lot, my body is constantly burning fats for energy (either dietary or stored bodyfat). Eating 150g per day, you certainly burn fats for energy at some level, although it might not be very significant. Some people force their bodies to switch over almost entirely to fat-metabolism by eating very low carb (usually under 20g of carbohydrate per day) and exercising. In that case, the body enters what is called “nutritional ketosis” and, if combined with a caloric deficit, will encourage the body to burn stored body fat for fuel.
This of course varies remarkably by person. I find it fairly easy to be “fat-fueled,” although I don’t care for eating as much fat as I do. Other people have a very difficult time getting their bodies to give up on carbs. Like diabetes, metabolisms are complex.
I tend to be in that second category – even after a week of very low carb eating (<20g/day, sometimes a LOT less), my body barely shows traces of ketones… Protein seems to be my metabolism’s fuel of choice, especially in the absence of “enough” carbs.
Yep. I actually eat far more carbs and protein than the “keto” folks, but have no problems staying in nutritional ketosis. My body seems to like burning fat as soon as I bring my carbs down to below 80g per day.
Definitely, my experiences broadly speaking with metabolism is that the more I learn and try different things the more complicated it seems to get!
One thing I struggle with on a low-carbohydrate diet is keeping my weight up. There is no way I could eat only 2300 calories a day, and keep my weight in an acceptable range. I do exercise maybe 3-4 times a week, but it’s not very intense, mostly rock climbing and hour long walks mixed with some basic strength training.
What I’m concerned about really these days is that I’m in some weird middle ground, where I eat too many carbohydrates to effectively metabolise fats, but that most my calorie breakdown still seems to come from fats.
Me too. I’m only on 2,300 because I’m traveling for work and can’t exercise like I normally do. I expect to lose 5 lbs ;( I’ve actually got an appointment to see an endo, since I’m pretty certain at this point I can’t maintain weight without changing my treatment regimen (and likely using at least bolus insulin). My actual “normal” daily kcal intake in order to not lose weight is about 3,100. I have a very difficult time actually eating that much protein and fat and keeping my carb intake low, so it’s something that is going to have to change.
I found exactly the same when I was eating under 50 grams of carbohydrates per day. When I was eating around 100 grams, I found if I was diligent, which meant ensuring I ate the same meals daily.
I have wondered if I can maintain weight, with a lower total calorie intake, by eating more carbohydrates. Perhaps my body deals more effectively with turning carbohydrates into muscle and fat.
When you reduce carbs, weight is increased by protein % intake. IF you have enough fat for energy. Where most go wrong, they simply don’t eat enough good fats. Fats by themselves won’t put weight on, but will give the fuel to burn, so you shouldn’t lose weight…
Bernstein added 500 fat calories to his skinny patients and no weight gain. It was only when he added protein the weight came on.
Overgeneralizing. I eat a much higher than normal protein proportion due to my lean muscle percentage and workout routine. I have no problems with not eating enough protein (30-35% of my calories are from protein, less than 10% from carbs, rest from fats).
Simply enough, metabolism is complicated. For some of us (especially Type 1s), low-carb means we’re in a crunch as far as weight loss goes. Lack of insulin makes gains of any kind more difficult, and just increasing protein doesn’t work for everyone.
The problem I’ve found in the past with increasing my protein enough to keep my weight stable is that it becomes increasingly more difficult to bolus for it with the larger amounts of protein.
I’m not 100% sold on the fact that Fats don’t increase weights. I’m sure Dr Bernstein did perform that test, but so much of what he says is largely anecdotal and never really backed up by clear peer reviewed evidence.
I imagine the problem is that there are largely dozens of minute metabolic processes, which may differ between each individually, so it’s likely very hard to give some absolute statement on fats increasing weight, or exactly how eating low-carbohydrate will impact you.
Which is both fascinating scientifically, and frustrating.
As I see it, you need to go back to carbs, the way you are doing low carb isn’t sustainable. normally protein is in the middle and like a seesaw, as the carbs come down the fats go up… low carb and low fat won’t work
Fats in general, don’t increase weight by themselves, They need the insulin and calories from carbs and helped by proteins. Your genes are another factor.
There was an experiment with a 5.800 cal LCHF diet and the subject put on a smaller amount than would be expected
