Body Weight Loss = Carb or Calorie Restriction?

For the last couple of years, I’ve been able to maintain my body weight between 170-180 lbs on my 5’10” frame, mainly by running regularly. In previous years, my weight has yo-yo'd much worse, and it seems to correlate with periods of nonrunning. For example:

• In pre-college years I was a skinny kid. At 18 I weighed 140 lbs at my current height. I was a very active runner and had no thought about how I ate.


• In my 20s I ran very little and my weight climbed up to 230 lbs. by the time I was 30. Again, I gave little thought to how I ate.


• In my 30s I trained for marathons and was able to lower my weight to 170 lbs. Injuries occurred from time to time and my weight would peak above 200 lbs. I started to care more about how much I ate, but didn't make radical changes to the type of foods that I ate.

This year (early 40s), I had to stop running in January due to an injury. It was bad timing (is an injury ever good timing?) because I was attempting to lose the annual weight gain from the holidays. I weighed 180 lbs. The table below summarizes what happened since the injury. Read on if you care to know the nitty gritty and my evolving opinion on low carb v. low calorie.


With no physical activity and not changing my food consumption for about a month my weight crept up. Ugh. The weight gain motivated me to change my eating habits. Marksdailyapple.com has become a popular site for diet and lifestyle. The site is authored by the six-pack toting Mark Sisson, who is also the author of the book "Primal Blueprint: Reprogram your genes for effortless weight loss, vibrant health, and boundless energy" (PB). Both the site and the book espouse paleolithic concepts.

To me the PB diet sounds similar to Atkins or South Beach via carb restriction: eating a lot of plant sources like vegetables and eating plenty of animal sources for fat and protein. The PB lifestyle part is about reducing stress, mainly by exercising less and sleeping more. PB exercise is relatively minimal: a few days doing 20-30 minutes of resistance exercise, a few days doing some low intensity cardio and a brief sprint once a week.

My first month of primal living wasn't very successful. I walked most days for 45 minutes (it was all I could do with the injury). Pasta casseroles were replaced with meats and veggies for dinner, and eating those leftovers for lunch. Sometimes for breakfast I ate eggs. I also ate my typical 3-4 servings of fruit per day, like 2 apples and 2 bananas. Despite these changes, my weight continued to creep up.

Comparing my flabby belly to Sisson's six-pack, I decided that I must not have been accurately following his PB program, so I bought his book to get more information. The PB weight loss plan was described in a nutshell on pg. 5:

"Driven by high fat/moderate protein/low carb diet, intuitive, sporadic meals, and exercise and Primal Exercise Laws. Don't worry about portion control, regimented meals, fanatical exercise or even family genetic disposition. Calorie restriction with extreme exercise leads inexorably to long-term failure. Bottom line: It's all about insulin to enjoy effortless lifelong weight control."

The low carb PB diet is defined throughout the book as a weight maintenance plan at 100-150 grams of daily carbs and weight loss plan below 100 grams of daily carbs (pgs. 66, 89, 90, 97, 105, 110, 223 and 227). Twice in PB, there is a chart called the "Carbohydrate Curve" (pgs. 90, 227) plotting daily carb consumption against weight gain. The curve repeats the message of weight loss below 100 grams carbs, weight maintenance between 100-150 grams carbs and weight gain above 150 grams carbs.

In my first month of primal eating, I don't know how many daily calories I consumed, but I'm positive my daily grams of carbs were higher than what Sisson recommended. I googled the nutritional data for apples and bananas (recall that I was eating approximately 2 of each daily). My consumption of fruit alone was about 124 grams of carbs, or 500 calories. More google searching showed why plentiful veggies are acceptable on this carbohydrate curve. Veggies have a low concentration of carbs, much lower than fruit.

The "Carbohydrate Curve" assumes that a person is getting adequate protein, fat and doing primal exercise (pg. 90). Recall that primal exercise is minimal, so for "heavy exercisers" or "the chronic cardio crowd" (high intensity endurance), Sisson recommends increasing carb intake to replace glycogen stores (pgs. 88, 110). The following recommendation is given on pg. 89:

"If you are insistent upon doing Chronic Cardio, you must increase carb intake to account for regular depletion of stored liver and muscle glycogen and an elevated metabolic rate. You can experiment with consuming perhaps 100 additional grams carbs per day for every extra hour of training and notice how your body responds. However, I'd prefer that you simply adjust your training program to conform to Primal Blueprint guidelines and thus reduce your need for dietary carbohydrate." (my emphasis)

It's curious to hear advise against long endurance activities from a former elite marathoner and triathlete. Sisson suggests that you are quite likely to fail at fat loss through high intensity cardio exercise. He recommends low intensity cardio and carb restriction (pgs. 174-5). It's suggested that eventual fat storage (weight gain) and/or metabolic problems are highly probable for the chronic cardio crowd who consume 150-300 grams daily carbs, and almost certain for those consuming more than 300 grams over an extended time (pg. 92). For an explanation why Mark recommends carb restriction, it can best be summed up by this quote on pg. 88:

"If you've forgotten everything you ever learned in biology, just remember this and own it: carbohydrate controls insulin; insulin controls fat storage." (his emphasis)

Carb restriction is a reoccurring message in PB, but the end of the book takes a twist. A sample calculation for losing weight is given where daily calorie intake is approximately 2000 calories and daily calorie expenditure is approximately 3000 calories (pg. 229). In chapter 8, "A Primal Approach To Weight Loss", the following is stated on pg. 223:

"Let's not mince words here. The science of reducing stored body fat requires you to burn more calories than you consume...losing one to two pounds of fat per week...means an average daily deficit of 500 to 1000 calories."

This seems contradictory. In the introduction of the book there was no need to worry about food portion control or restricting calories (pg. 5). If I want to lose weight I have to restrict carbs AND calories? A couple of paragraphs below the above quote, Sisson seems to suggest that carb restriction is the key to fat loss:

"Primal Blueprint-style eating allows you to eat more calories than a restrictive diet yet be far more successful losing body fat. This seemingly illogical claim has played out in numerous studies where control groups ate the same number of calories and had the same activity level but ate different kinds of foods. The disparate results achieved were attributed to what scientists call a metabolic advantage provided by eating certain foods (namely, those that moderate insulin production)."

Given my first primal experience not counting grams or calories, I proceeded to revise my diet by restricting both carbs and calories using a food log. I restricted grams of carbs to under 100 daily and restricted calories to 2000 daily. I also was targeting about 140 grams protein and about 120 grams fat. My physical activity still consisted of almost daily 45 minute walks. For about sixty days, I followed this plan. Macronutrient's statistics of my food log are given below.


On average, I met my daily target macronutrient goals and overall calories. In 2 months, I lost 8 lbs. The food log was a bit cumbersome. I created a spreadsheet to track macronutrients and servings. I commonly weighed my food in the beginning, but after some experience, I started to estimate serving size based on volume. The amount of standard deviation is probably based more on my estimation accuracy than actual daily variation in macronutrients.

After a couple of months (April and May), I became complacent and stopped logging food. I didn't change the types of foods that I was eating. I ate based more on hunger. It was also at this time that I started to run again, albeit at a very easy pace. It's difficult to say if I consumed more carbs and/or more overall calories over the next two months, but I gained some weight back despite being more active.

After a couple more months (June and July), I became frustrated with the weight gain and went back to food logging. It was also about this time that I started training with my son's cross country team in earnest, so my physical activity increased again including high intensity running. Macronutrient's statistics for August are given below. Within 1 standard deviation, my nutrition was the same as the previous food log.


In a month, I lost 8 pounds, or twice the weight loss rate as earlier. During both periods of time that I kept a food log, a typical week day for nutrition looked like this:


It seems that I have proven through my self-experimentation that the documented combination of low carb and low calorie is effective at weight loss, despite whether the activity level is low intensity walking or high intensity running, although the level of activity affects the rate of weight loss. It's important to also note that during the period of low carb high intensity running, there were times when I experienced fatigue. Specifically, there was a cross country interval workout where we sprinted 16x200s with 45 seconds rest in between. I was fine for the first 13x 200s, but in the last 3x 200s I was very tired and could only manage to jog behind the kids.

But I haven't proven if it's necessary to combine low carb and low calorie to lose fat. Could I continue to eat low carb below 100 grams, but double the calories to 4000 and still lose weight (thus testing the metabolic advantage, PB, pg. 224)? It's not unreasonable to suggest that the months that I intended to eat primally but didn't keep a food log could have been low carb-high calorie, and were not effective for weight loss. However, it's not conclusive because I didn't document my nutrition.

Or could I quadruple carbs to 200-250 grams but continue low calories at 2000 and still lose weight (carb intake where Sisson said chronic exercisers would eventually store fat, PB, pg. 92)? Since I'm still training at high intensity levels with the cross country team, I'm going to choose to change my diet to add more carbs, but continue to restrict calories to 2000.

A future post will be specifically how I'm changing my diet.