Energy Expenditure in Hunter Gatherers

We are told that our western lifetyle is to blame and that all we need to eat less and move more. And that sounds intuitively true. The move more part was challenged by a study of the Hadza people (Pontzer H, Raichlen DA, Wood BM, Mabulla AZP, Racette SB, et al. (2012) Hunter-Gatherer Energetics and Human Obesity. PLOS ONE 7(7): e40503.).

…average daily energy expenditure of traditional Hadza foragers was no different than that of Westerners after controlling for body size. The metabolic cost of walking (kcal kg−1 m−1) and resting (kcal kg−1 s−1) were also similar among Hadza and Western groups.

The similarity in metabolic rates across a broad range of cultures challenges current models of obesity suggesting that Western lifestyles lead to decreased energy expenditure.

We hypothesize that human daily energy expenditure may be an evolved physiological trait largely independent of cultural differences.

Interesting article (What a hunter-gatherer diet does to the body in just three days).

My other lasting impression was how little time they spent getting food. It appeared as though it took just a few hours a day — as simple as going round a large supermarket. Any direction you walked there was food — above, on and below ground.

MAF Training And Metabolic Syndrome

There’s an interesting study which looked at two months of training at FATmax to see what the effects on Metabolic Syndrome (Dumortier M, Brandou F, Perez-Martin A, Fedou C, Mercier J, Brun JF. Low intensity endurance exercise targeted for lipid oxidation improves body composition and insulin sensitivity in patients with the metabolic syndrome. Diabetes Metab. 2003 Nov;29(5):509-18). The study showed good improvements from MAF level of training intensity.

The patients exhibited a significant reduction in body weight (- 2.6 +/- 0.7 kg; P=0.002), fat mass (- 1.55 +/- 0.5 kg; P=0.009), waist (- 3.53 +/- 1.3 cm; P<0.05) and hip (- 2.21 +/- 0.9 cm; P<0.05) circumferences, and improved the ability to oxidize lipids at exercise (crossover point: + 31.7 +/- 5.8 W; P<0.0001; LIPOX(max): + 23.5 +/- 5.6 W; P<0.0001; lipid oxidation: + 68.5 +/- 15.4 mg.min(-1); P=0.0001). No clear improvement in either lipid parameters or fibrinogen were observed.

There were significant improvements in the markers of Metabolic Syndrome.

The surrogates of insulin sensitivity evidenced a decrease in insulin resistance: HOMA%S (software): + 72.93 +/- 32.64; p<0.05; HOMA-IR (simplified formula): – 2.42 +/- 1.07; P<0.05; QUICKI: + 0.02 +/- 0.004; P<0.01; SI=40/I: + 3.28 +/- 1.5; P<0.05. Significant correlations were found between changes in body weight and HOMA-IR and between changes in LIPOX(max) and QUICKI.

Here’s a longer term study which shows positive results over a longer time period (Drapier E (2018) Long term (3 years) weight loss after low intensity endurance training targeted at the level of maximal muscular lipid oxidation. Integr Obesity Diabetes 4).

Average weight loss was -2.95 ± 0.37 kg after 3 months, -4.56 ± 0.68 kg after 1 year, -5.31 ± 1.26 kg at 2 years and -8.49 ± 2.39 kg at 3 years.

The beauty of this study was that it compared low intensity exercise to a low fat diet.

This study shows that this low intensity exercise training maintains its weight-reducing effect 3 years while diet is no longer efficient, and that this effect is initially related to muscular ability to oxidize lipids but that metabolic and behavioral adaptations have been further developed and contribute to a long lasting effect.

The results are powerful.

Here’s a third related study (J. O. Holloszy and E. F. Coyle. Adaptations of skeletal muscle to endurance exercise and their metabolic consequences. Journal of Applied Physiology 1984 56:4, 831-838).

The major metabolic consequences of the adaptations of muscle to endurance exercise are a slower utilization of muscle glycogen and blood glucose, a greater reliance on fat oxidation, and less lactate production during exercise of a given intensity.

These adaptations play an important role in the large increase in the ability to perform prolonged strenuous exercise that occurs in response to endurance exercise training.

From the results:

…Probably the most important of these is an increase in mitochondria with an increase in respiratory capacity. One consequence of the adaptations induced in muscle by endurance exercise is that the same work rate requires a smaller percentage of the muscles’ maximum respiratory capacity and therefore results in less disturbance in homeostasis.

A second consequence is increased utilization of fat, with a proportional decrease in carbohydrate utilization, during submaximal exercise.


Polar App Zones

The heart rate zones in the Polar Flow app are misleading. Here’s a recent run.

The problem with the Polar app is that the zones are based on assumptions which may not apply for you. More specifically your fuel is a mixture between fat and carbohydrates and the hard edges these applications show don’t reflect a mixture.

I had my own VO2max tested in a lab. I know what my fuel mixture is at a particular heart rate. My Polar app shows me in fat burning below 111 bpm and “fit” above that point. My MAF range is 112-122. My VO2Max test showed my fat/carb burning at 90% / 10% at a heart rate of 124.

But I am fat adapted keto for two years so I am primarily a fat burner. This is why MAF works well for me. My 100% fat burning heart rate is 117 which center of MAF. As long as I am in the MAF zone I’m burning nearly all fat – even though the Polar Flow program says otherwise.

FASTER Study – Three Hour Magic Number

In previous posts I’ve taken a critical look at the FASTER study (FASTER Again – Checking a number on Ben Greenfield’s data). In particular, I took at look at Ben Greenfield’s three hour data (FASTER10 – Ben Greenfield – Three Hour VO2 testing). Ben looked like he still had gas left in his tank after three hours of sub-maximal running.

The Vegan

But what about Damian Stoy (FASTER Subject 43)? He’s a vegan who is not at all fat fueled. He never got more fuel from fat than 50% and that was at 45% of his VO2max.

At 64% of VO2max, Damian was getting nearly zero of his energy from fat. His carbohydrate oxidation rate was ~10 kcal/min. So, in three hours of running, Damian burned ~1800 kcals which has to be close to his entire glycogen stores.

My conclusion? Beyond this time and intensity being carb fueled isn’t a great choice. The reason that marathons are 26 miles is historical and practical. People just can’t run hard for longer times.


CrossFit Injury Rate Study

Interesting study of CrossFit injury rates (Hak PT, Hodzovic E, Hickey B. The nature and prevalence of injury during CrossFit training. J Strength Cond Res. 2013 Nov 22.). The study reported on an on-line survey so it was probably quite slanted in the results.

An online questionnaire was distributed amongst international CrossFit online forums. Data collected included general demographics, training programs, injury profiles and supplement use. A total of 132 responses were collected with 97 (73.5%) having sustained an injury during CrossFit training. A total of 186 injuries were reported with 9 (7.0%) requiring surgical intervention. An injury rate of 3.1 per 1000 hours trained was calculated.




Fat Burning – Running vs Cycling

In a previous post I took at look at the exercise intensity which produced the maximum fat oxidation rates (Maximal Fat Oxidation Rates in an Athletic Population). A study took a look at the fat oxidation rates which happen when exercise is performed at the FATmax rate with cycling and running.

There was a significant difference in the rate of fat oxidation between the two (Juul Achten, Michelle C Venables, Asker E Jeukendrup. Fat oxidation rates are higher during running compared with cycling over a wide range of intensities. Metabolism, Volume 52, Issue 6, June 2003, Pages 747-752.).

Maximal fat oxidation was 28% higher when walking [ed: did they mean running?] compared with cycling, but the intensity, which elicits maximal fat oxidation, is not different between these 2 exercise modes.

These are interesting results. Although both exercises were done at the same intensity level (as measured by heart rate) they resulted in different amounts of total fat oxidation.

This leads me to conclude that although cycling and running can be both done at the MAF heart rate they are not equal for fat oxidation rates.

What About Rowing?

It would be interesting to see what the fat oxidation rate at FATmax is for rowing (ROW) and other modes. Turns out there’s a study for that too. (Egan B, Ashley DT, Kennedy E, O’Connor PL, O’Gorman DJ. Higher rate of fat oxidation during rowing compared with cycling ergometer exercise across a range of exercise intensities. Scand J Med Sci Sports. 2016 Jun;26(6):630-7. The study found that:

…FATox is higher during ROW compared with CYC exercise across a range of exercise intensities matched for energy expenditure…

The details show:

Despite similar oxygen consumption, rates of fat oxidation (FATox ) were ∼45% higher during ROW compared with CYC (P < 0.05) across a range of power output increments.

The crossover point for substrate utilization occurred at a higher relative exercise intensity for ROW than CYC (57.8 ± 2.1 vs 42.1 ± 3.6%VO2peak , P < 0.05).

Putting the Pieces Together

  • Rowing is ~45% better than cycling.
  • Running is ~28% better than cycling.
  • Rowing should be ~17% better than running.

Mechanism to Explain Differences

The degree to which an exercise engages muscles determines the maximum fat oxidation. Rowing has more muscle involvement than running which has more muscle involvement than cycling.




FATmax Training Results

In principle, training at FATmax (Maximal Fat Oxidation Rates in an Athletic Population) should result in significant loss of body fat and the resulting improvement in body composition. However, it is something of a surprise just how few studies have been performed to determine the effectiveness of this type of training. A meta-analysis (A. J. Romain, Physical Activity Targeted at Maximal Lipid Oxidation: A Meta-Analysis. (J Nutr Metab. 2012; 2012: 285395.) took a look and only found 15 total studies of this subject which fit their criteria. These studies were relatively small but the results were encouraging.

This meta-analysis confirms the conclusions of the individual studies, that are very low intensity training targeted at the level of maximal fat oxidation significantly decreases body weight, fat mass, waist circumference and total cholesterol. On the average, the effects of this variety of training are thus well confirmed, and their average magnitude is more precisely described.

Study Limitations

Only 5 studies include a control (nonexercising) group. There were also no longer term studies.

Volume of Training

Interestingly, some studies demonstrated an important average weight loss (8 kg over two months) with a protocol based on 90 min/day exercise at the level of maximal lipid oxidation. This could suggest that large weekly volumes of exercise training may be much more efficient than those used usually (i.e, 3 × 45 min/week).

Loss of Visceral Fat

The study called out a reference paper (Ohkawara K, A dose-response relation between aerobic exercise and visceral fat reduction: systematic review of clinical trials. Int J Obes (Lond). 2007 Dec;31(12):1786-97. ) which indicated that there is a dose response between aerobic exercise and loss of visceral fat.

… at least 10 METs x h/w in aerobic exercise, such as brisk walking, light jogging or stationary ergometer usage, is required for visceral fat reduction, and that there is a dose-response relationship between aerobic exercise and visceral fat reduction in obese subjects without metabolic-related disorders.