The Carb Threshold

Regarding my notes on the Kekwick diet research, a reader writes:

Very interesting results. However, if you take the same proportions of macro-nutrients in what you are currently eating, and reduce them all by the same amount (reducing calories, keeping same % of macro-nutrients), then you will loose weight acording to the usuall 3500Kcals = 1lbs formula.

I also wonder if there has been research where there was not such a huge differential (90%) to try to determine at what % the carb-insulin fat-increase effect takes place.

It is true that if you reduce calories far enough–regardless of the ratio of the macronutrients–that you will lose weight. The problem is what happens to your body as you do that. As the Kekwick research and other research has shown, a high-carb ratio has the effect of inhibiting weight loss in the calorie range where most people are comfortable. In other words, in order to consistently lose weight with a high-carb diet, many people have to reduce their calorie intake so far that the diet becomes torture for them to stay on, and they drop off it without making substantial progress toward their weight goals.

(Incidentally, the 3550 calories = 1 pound formula is an average based on the metabolism Americans tend to be in. For individuals, the actual amount will vary considerably.)

There has been research done on where the threshold is for weight gain, and the answer is interesting. First, there are two thresholds, one above which a person will gain weight (i.e., eat X number of carbs per day or more and your body will start storing new fat) and one below which one will lose weight (i.e., eat Y number of carbs per day or less and you will start burning fat).

Where these two thresholds are varies considerably from one individual to another. Some people are much more prone to weight gain or resistant to weight loss than others.

The thresholds also vary depending on the metabolic state that the individual is in at the time. This varies based on a variety of factors, including exercise and total caloric intake. For example, if you were to eat 10,000 calories per day, you’d probably gain weight even if none of them were from carbs, and if you ate 500 calories per day, you’d certainly lose weight even though all of them were from carbs.

FWIW, Atkins encourages people to find where their own thresholds are in the zone where they are comfortable eating (i.e., where they don’t feel like they are starving or gorging themselves). For most people, the number of carbs they can eat in this zone and still lose weight is rather low, but as one makes progress toward one’s weight goal the amount goes up until, when one arrives at one’s goal, one eats enough carbs to maintain one’s weight without losing further and without gaining weight back.

If you’d like the details of the approach, check out the book.

I did after my doctor recommended a few years ago that I go on the Atkins diet (which was much harder then than it is now, what with all the new low-carb products on the market). I lost seventy pounds before hitting a plateau (which I now think was due to slipping out of good diet habits), but I kept the weight off. Late late year I took a few months off from the low-carb approach to let my metabolism re-set, then went back on in mid-January. Since that time, I’ve lost over 40 pounds, an average of two pounds a week, without being hungry and feeling better than I had in years before discovering the diet.

Incidentally, the picture of me that you see on the blog is me before going back on the diet. I need to get a new one made, because I’m now quite a bit thinner than I am in that one.

Author: Jimmy Akin

Jimmy was born in Texas, grew up nominally Protestant, but at age 20 experienced a profound conversion to Christ. Planning on becoming a Protestant seminary professor, he started an intensive study of the Bible. But the more he immersed himself in Scripture the more he found to support the Catholic faith, and in 1992 he entered the Catholic Church. His conversion story, "A Triumph and a Tragedy," is published in Surprised by Truth. Besides being an author, Jimmy is the Senior Apologist at Catholic Answers, a contributing editor to Catholic Answers Magazine, and a weekly guest on "Catholic Answers Live."

3 thoughts on “The Carb Threshold”

  1. Jimmy,
    But with all the low carb products on the market, I think it will make it harder for people to stay on the Atkins diet. Instead of eating a burger without the bun & no snack, people will eat a burger with low carb bread and an Atkins snack.
    This is what happened to people on low-fat, low cal diets when fat free yogurt, etc. became available.

  2. Personally (and I’m the commenter you quoted), I found that the 3500 Kcals = 1 lbs equation worked for me. 500 kcals a day less, and I was loosing ~1lbs a week.
    Thinking back, the main thing I cut out was refined sugar, especially in the form of pop. Switching to Diet Coke (.41Kcals / 100ml) vs Coke (41Kcals / 100ml) with one Super Big Gulp per day (1.3L) reduced my intake by ~527Kcals/day – which was all it took to reduce my calories enough to loose that weight – but looking back, it was all carbs.
    I still eat a fairly high-carb diet, I believe. However, most of my carbs are complex carbs (wheat alergies, so we use spelt, ezekiel bread, etc.).
    Anyway, it’s all very interesting stuff.

  3. There is a lot of conflicting information today on what constitutes a proper diet.
    I do not find quoting scientific studies sufficient because both (all!) sides have studies that support opposing positions. So I try to balance science with what I find in the Bible, Church teachings, lives of the saints, etc.
    I also try to look at things historically. The work of Dr. Weston A. Price is an example of this. He investigated traditional diets of indigenous peoples and compared them to their neighbors who had switched to more modern diets. He found distinct patterns in how peoples in widely varying cultures produced, preserved and prepared their food, and in the health benefits they derived from those traditional methods. This makes sense to me. God didn’t leave man to struggle with poor diet and nutrition until the twentieth century. Mankind has lived for hundreds and thousands of years and gotten along just fine without the inventions of modern science and the food industry.
    I use the same line of argument against those supporting contraception: “So you mean God didn’t intend for couples to have a bunch of kids but he was just waiting for modern science to come along with convenient contraception to solve this little problem for him?” In other words, if something was good enough for man for all those centuries, maybe God has a reason for it. It is only in our “chronological snobbery”, as Cal Thomas calls it, that we think WE know so much better now.
    So, while all the current debate about diet and nutrition is well and good, I would dearly love to hear this topic discussed from the perspective of Scripture, the Church, lives of the saints, etc.
    Bread seems to be on the “No” list these days and yet the Bible considers bread the most quintessential of foods. What about the diets of monks and religious? Can we dismiss that as merely penitential? Was God calling them to ruin their health or could there actually have been health benefits? Some of those folks lived awfully long lives.
    I would greatly appreciate if anyone could point me to more information on this.
    Thank you and God bless!

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