So, what happens just above the ketogenic threshold?


(BuckRimfire) #1

TL,DR: What fat metabolism happens when you’re eating 75 g/day carbs?

Maybe I’ve read this before but just forgot, but I’m wondering what metabolism is going on when one is eating “too much” carb to be in the canonical keto range, but not enough to meet much of your needs?

I’m 6’ tall, weight 157# for the past 23 years (except briefly went up 6# 1.5 years ago, and went down again when I barely reduced carb intake, as in: from 4 servings of pasta to 3 per meal) so BMI just over 20. I started lazy keto/low carb in late June last year. My weight dipped about 3 pounds in the first few weeks then came back to 157 and is steady.

My job is only semi-sedentary: I work in a biological research lab, so I’m up on my feet at the bench and up and down the hall quite a bit. I mostly avoid the elevators so I’m trotting up 10 to 15 floors of stairs in an average day. Other than that, I exercise sporadically, of late. In the last two weeks, I did one strenuous 3 hour river kayaking trip, one 5 mile walk around the city with some hills while wearing a 35# backpack and heavy hiking boots, one unweighted 2 or 3 mile walk, one 45’ lake kayak paddle (fairly high aerobic pace), one 3 hour river kayak trip that was mostly hiking in and portaging over boulders instead of kayaking, and one 6 hour/20 mile sea kayak trip (low-medium aerobic pace). That was a bit better than average two weeks vs the last year overall, but clearly, my metabolic needs are a little above “sedentary.”

So, I’m not in the strict keto range (which I understand as < 100 Kcal/day in dietary carbs), but I’m not losing weight. I eat a lot of nuts, a tiny amount of fruit, an occasional beer (like, one or two per week), an average of one serving of low carb bread or tortilla per day (we avoided these for the first few months), and, as you’d expect, a lot of meat, fish, cheese, butter and heavy cream.

I rarely add it up carefully, but I think I’m probably averaging 250-300 Kcals of carbs per day. Basically the Atkins Maintenance range? That’s clearly not enough to support my metabolic needs, but I’m not losing weight and the mirror says I’m not burning muscle (as does my ability to drive my kayaks around about as well as ever). So, what the heck am I burning if I’m not quite “ketogenic?”


(Ethan) #2

It depends on your metabolic situation. As a severe T2DM with a lot of insulin resistance, I was keto from 9/2013 until 5/2014. Then I went low carb—about 60g a day—but not ketogenic. I had occasional higher carb days—maybe a date at melting pot—but usually stayed at about 60g. By 1/2016, I had gained about 60 pounds.


(Allie) #3

Apparently you get stuck in low carb purgatory because your carbs are too low to provide enough fuel for your body to run on, but too high to produce ketones so you just feel like crap.


(BuckRimfire) #4

By that assessment, I should feel like crap, but I don’t. Admittedly, I’m one of the most insulin-sensitive 54-year-olds you’ll find, I think.

To make the point more specific: On Wednesday, I had a typical diet for me. Forgot what I had for breakfast (probably eggs and bacon or sausage), but lunch was a 14 oz can of pink salmon, a few oz of cheddar cheese and a couple of big handfuls of walnuts. Wed. evening after work was the river kayaking trip that was three hours, mostly hiking with the boat and clambering over piles of rocks, not paddling. Had a Burger King bacon double-cheeseburger minus the bun immediately after, then drove home (45’), had a big serving of chili verde that I’d made on Sunday to this recipe https://tastesbetterfromscratch.com/pork-chile-verde/ and got six hours of sleep. Thursday I took vacation from work because I’d been trying for years to get a neighbor out on my favorite long sea kayak day trip, and he has a weird schedule (airline pilot) so weekends had never worked out. I had four fried eggs (with a little sauted onion and a half-dozen grape tomatoes), some more chili verde, two big cups of tea with cream and 1/8 of an orange. We then kayaked 20 miles in six hours of paddling plus one hour of breaks. I ate one largish tin of Trader Joe’s kippered herring, a small piece of turkey jerky my buddy pushed on me (pretty sweet so a bit of sugar there, but it was a tiny serving), and a couple of handfuls of walnuts. I drank a liter of black tea that contained a couple of tablespoons each heavy cream and unrefined coconut oil, also. I felt great all day and consistently out-paced my buddy when I wanted to speed up, including the last half mile or so to the dock in which I pulled out about a three minute lead on him. Admittedly, I have a slightly faster boat (longer and a little narrower), but it’s also heavier and he is a bit bigger than me (taller and heavier, but not fatter) and a well-experienced paddler, so I didn’t have a huge advantage in equipment or training. I’m definitely not lacking energy!

Again, this level of carb is recommended for maintenance in Westman, Volek and Phinney’s 2010 Atkins book. I just don’t want to re-read the whole book looking for what, if anything, they give for an explanation of metabolism at this level.


(Alec) #5

You burn the carbs first, then you burn fat. Ketones are only made in the liver, and are a by-product of fat burning in the liver. However, the vast majority of your muscles can burn fat for fuel (better if they are fat adapted), and do so if their glycogen gets low.

On say 100g of carbs a day, you would be going in and out of ketosis (ie producing ketones) depending on the timing of your meals.


(BuckRimfire) #6

OK, so breaking down triglycerides and directly using fatty acids in catabolism, rather than getting ketones from the bloodstream? If so, that sounds like the pathway I was forgetting.


(Alec) #7

Correct. There was another thread recently where we discussed this, and we agreed that although we do burn ketones in ketosis, the majority of energy used is actually fatty acids in the muscles, not ketones. Ketones are generally saved for use by the organs that really need them: heart and brain.


(Bunny) #8

You could be just burning dietary fat (if you can see some ketones?) and carbohydrates (glucose) being that your glycogen stores are always full (no body fat will ever get burned the way you would like)?

Your gaining muscle mass with exercise thus increasing your storage of glycogen from fatty acids FFA’s, ketones, glucose and possible others?

If your gaining lean tissue (muscle) the more energy expenditure (through caloric restriction, fasting or exercise) you need to deplete glycogen storage from the liver, muscle and adipose tissue before you can burn ACTUAL body fat?

If your maintaining a certain body fat and lean tissue weight then your in a balance of partial depletion and replacing of glycogen?


(Karim Wassef) #9

You lose lean mass and lower your metabolism.

You burn some fat, but it’s trapped behind a locked insulin freezer door. The door unlocks/thaws temporarily so you can be in keto for some time, but once that door is locked, you’re either using the glucose or storing it as fat while your body uses lean mass and throttles your metabolism to be as sluggish as possible.

It’s calorie restriction… which has temporary ketosis with all the negative side effects of SAD.


(Bacon is the new bacon) #10

@BuckRimfire There are really two questions here. The first one is what your insulin threshold is, so we can determine whether you are eating above or below it. Then we can answer the question of what your body is probably doing.

Eat enough carbohydrate for the glucose in it to become a problem for your body, and insulin secretion will raise high enough to drive it out of the bloodstream and into fat tissue in the form of triglycerides and into muscle to be either metabolized or stored as glycogen (a certain amount can also be stored as glycogen in the liver, as well). The degree of insulin response depends on the extent to which your cells have down-regulated their insulin receptors; the more insulin-resistant they are, the more insulin is required to have the same effect. That level of incoming glucose also drives down glucagon secretion, thereby raising the insulin/glucagon ratio and halting ketogenesis and gluconeogenesis (so as to give priority to metabolizing and storing the dietary glucose and avoid making more).

There was a corporate physician in the 1950’s (at Dupont, I believe) who had great success putting his workers and executives on a low-carbohydrate diet. One of the case studies he published was of an executive who was so insulin-resistant that a single apple was enough to halt his weight loss and start him gaining again.

Eat a small enough amount of carbohydrate, and your glucagon goes up, driving your insulin/glucagon ratio down, and initiating gluconeogensis and ketogenesis, the idea being that a low glucose intake means that the liver needs to make glucose for those cells that absolutely must have it, and ketones for the rest.

An excessive serum glucose is dangerous for a number of reasons (advanced glycation end-products and coma or death from hyperglycemia being the two most important), so the body gives priority to storing and/or metabolizing glucose (this would likely have evolved as a defense against the ingestion of ripe fruit during late summer/early fall; the advantage of storing fat for the lean winter months is obvious). Chronically elevated insulin also has deleterious effects, such as systemic inflammation, reduced ability to cope with oxidative stress, higher blood pressure, stiffer blood vessel walls, that sort of thing.

The point of a well-formulated ketogenic diet is to eat a small enough amount of carbohydrate to keep insulin low enough for as much of the day as necessary for advanced glycation end-products and elevated insulin not to be a problem for the body. What your actual carbohydrate tolerance/insulin threshold is depends on a number of factors, including both your genetic makeup and your dietary history (and resulting level of insulin resistance).

Under ideal circumstances, insulin rises modestly as we eat, to encourage the storage of energy in the adipose tissue. Then, when the fat cells have enough in storage, they secrete lepting to communicate that to the brain, and insulin is low enough for the signal to get through to the hypothalamus. The brain then shuts off ghrelin secretion, we stop being hungry, and we stop eating. During the period between meals, and especially during the overnight fast, insulin drops and the adipose tissue releases fatty acids as a source of energy to the body. The adipose tissue thus acts as a sort of metabolic flywheel, storing energy as it comes in and doling it back out between meals.

If you have any excess stored fat, eating carbohydrate below your threshold (whatever it is) will allow your body to set your appetite to the proper level for fueling your daily energy expenditure out of a combination of your dietary calories and calories from some of that excess fat. As long as you keep eating enough protein and fat to satisfy your hunger, you will automatically eat at the proper level and avoid triggering a famine reflex (in which the body hangs on grimly to its fat store, to get you through the famine). As your fat store drops to the level your body currently considers ideal, your appetite automatically rises to the level necessary for fueling your entire energy expenditure (since you no longer have extra fat to contribute to the process). The key is to eat in a hormonally advantageous way; trying to manipulate caloric intake or energy expenditure usually provokes an undesirable reaction from the body.