Inactivity and Metabolic Health V

It’s time for another installment in my Inactivity and Metabolic Health Series! For your consideration today is the small but interesting study from the Washington University School of Medicine in St. Louis, Missouri:

Improvement in Glucose Tolerance After 1 Wk of Exercise in Patients With Mild NIDDM

There were only 10 middle aged men in this study. While it’s true that studies this small can’t automatically be extrapolated to apply to everyone, what I’m trying to show people through this series is that each small study serves as a data point in a broader constellation of evidence. There is quite a vast body of evidence that inactivity is a primary driver of metabolic dysfunction, and even though no single study can ever be taken of irrefutable evidence of anything, when dozens, hundreds or even thousands of studies all show similar results across population groups, one must sit up and take notice. You can prove pretty much anything if a single study is your litmus test (broccoli will kill you! I saw a study!). What does the weight of evidence say, though?

On to the study. 7 of the men in this study had mild NIDDM (non-insulin dependant diabetes mellitus) and 3 had impaired glucose tolerance (ie, they hadn’t been diagnosed with NIDDM yet but had the precursors). They were instructed not to change their diets over the course of the study, and kept food logs that were analyzed by a dietician to ensure that study results weren’t confounded by diet changes. They were given an initial Oral Glucose Tolerance Test, a physical exam (including blood lipid panel), and a maximal treadmill exercise test before study onset to establish baseline values.

The subjects engaged in a 7 day exercise program consisting of 50-60 minutes on a treadmill or ergometer, working at 60-70% of their maximum heart rate. On the 8th day they were given a second OGTT and exam. On the 9th day they were given a second treadmill test.


VO2 max, body fat percentage and weight all remained unchanged after the 7-day exercise program, so those factors did not confound the results. There was a 36% decrease in plasma glucose, a 32% decrease in plasma insulin concentrations, and a 32% decrease in triglycerides.

What is notable here is that the subjects’ insulin response to a glucose load (from the OGTT) was significantly lower than it had been before the study. What this means: their bodies released less insulin in response to the same amount of sugar after exercising for 7 days. This is significant to the Great Sugar Narrative that holds that sugar is the driver of insulin production and release. Clearly exercise is a pertinent factor here that is ignored by the sugar-causes-diabetes contingent. Exercise can mitigate the insulin response to sugar.

Plasma glucose also decreased, even with a decreased insulin response, which indicates that the cells ability to respond to insulin also improved. From the study:

“The results of this study show that regularly performed vigorous exercise can result in a significant improvement in glucose tolerance in some patients with mild NIDDM. This improvement occurred despite a significantly smaller increase in plasma insulin levels. it appears that the improvement in glucose tolerance was due to a decrease in resistance to insulin.”

Also of note: triglycerides decreased 32% with no change in diet.

Bottom line: exercise reduces insulin response AND makes the body more sensitive to the action of insulin. Exercise does lots of other groovy things too.

Keep moving.

35 thoughts on “Inactivity and Metabolic Health V

  1. It’s hard to believe that there are still people sitting around who don’t exercise but there are.

    • In our culture, exercise is usually framed as simply a means to either burn calories or achieve a physique aesthetic. I think this makes people for whom those aren’t important considerations think that exercise isn’t relevant to their situation.

      • This is true in many cases especially in the diet/weight loss/exercise blog-o-sphere; however, in the public health community there is a huge push to move for health reasons where the focus is less on aesthetics and more on overall well being and health. This is great progress!

        • Yes! The public health and scientific/medical communities are beginning to really recognize the need for movement for health. it’s too bad the fad diet industries do such a great job vilifying the public health and medical communities!

          • I know! I’ve worked in PH for many many years and I can attest to the fact that we’re not out to get you and force you to eat horrible things and take drugs :) Working at the population level, we want people to be happy and healthy!

            Usually, the need for a quick fix is coming from the clinical patient who doesn’t want to do the moving or who feels helpless and desperate and frustrated because of (insert weird food belief here). A scapegoat is much sexier than going for a walk everyday :) Love your work, keep it up girl!

  2. I am hypoglycemic and find that any heavy exercise makes me feel awful. My blood sugar gets a lot worse.I have a couple of friends with the same issue. Maybe the lessening if insulin production makes me worse? I feel okay with light swimming and walking, but I’ve read those don’t do much for you. It’s hard to know what to do.

    • Actually, light to moderate exercise is just as beneficial! This study looked specifically at vigorous exercise, but other studies have shown benefits from much less intense forms of physical activity!

      • That is good to know, gokaleo. Do you have any posts about those, or can you link to them? I’d be interested. Thanks for this.

      • Isn’t it refreshing to get this kind of answer instead of some flip remark that makes you feel like a failure?! Go go kaleo!!

        • “working at 60-70% of their maximum heart rate.”

          I thought that 60-70% MHR was light to moderate.

          • Yes, 60-70% is fairly moderate in my opinion also, but this study classified it as vigorous. *Shrug* Perhaps it IS vigorous by US standards?

    • Andrea, I am also hypoglycemic. I’ve fallen off the exercise wagon and am about to get back on, but generally speaking, I find eating a small/medium meal of protein/complex carb/fat right before working out (and a snack after) is crucial (e.g., sauteed chicken breast and veggies, salad, quinoa, raw almonds, small amount of cheese). Also eating multiple times a day to keep BS stable, getting plenty of sleep, and avoiding exercise until afternoon while BS recovers from overnight fasting. My general workout is 40-60 minutes of cardio a day (stationary bike at gym or brisk walk) and 45 minutes of circuit weights three times a week. I do not consider myself an athlete, just want to be healthy, and I stay away from intense workouts like Crossfit or any significant activity in hot weather. “The Low Blood Sugar Handbook” by the Krimmels is *by far* the best info I’ve found on how to manage hypo.

  3. Since this is an article with only male participants… my father is 81. He was a cabinet builder and spent most of his life doing cabinet construction and other physically active work. As he has aged over the years (and since he now lives alone) the amount of construction type work he can do has been drastically reduced. He has a super-basic stationary bicycle that has no adjustments other than a timer and started riding it 5 minutes a day. He’s now up to 10 minutes a day and sings the praises of exercise loud and long. He had been plagued with some pretty severe cramps and since exercising (and using putty to exercise his hands, which are critical to his woodcarving) he has virtually no cramps at all. It’s kind of motivational for me, to see how much good has come from such basic regular exercise in an 81 year old man who has led a pretty hard life.

    • Love this! Thanks for sharing! My dad was a construction worker, avid outdoorsman, but since retiring his health has declined significantly. He’s got a treadmill now and I hope he feels better soon, too, so he’ll keep up with it.

  4. Your blog is scary… scary AWESOME!!! Remember when people started using “bad” and “sick” to mean the exact opposite? Yeah, well, I love that fun with word meanings stuff. So, yeah, your blog is SCARY, dude! '? Much love to you, lady. Keep on eatin’ the food and movin’ your butt. Woot!

  5. l did nothing but walk the first year of my “From Dud To Stud” program as I was obese at the time and had been sedentary for over a decade, then I very gradually increased the intensity over a period of three years, now in year five I’m game for anything.

    Whenever I try something new I think of the movie “What About Bob?” with Bill Murray and tell myself “Baby steps, baby steps!” I try to challenge myself while refraining from torturing myself.

  6. I began running, doing triathlons, and eating a healthy vegetarian diet 4 years ago. As a result, I lost 70 pounds and got into the best shape of my life. But it was at this point that I began having blood sugar issues while running. I’m unable to consume any sort of gu, gel, shot block, etc. that are designed for runners because they send me into a blood sugar roller coaster. According to all of the studies, my insulin and metabolic health should be top notch….I just don’t understand why this is happening to me after doing everything right

    I’ve been to several medical doctors and a naturopath (who diagnosed me with adrenal fatigue, LOL) and none of them have any answers either. By the way, my fasting insulin is >2.

    I would really, really, really be interested to see what you thought about this? Please?

      • I was definitely under eating when this all began, but since then I’ve gained back 10-12 pounds (mostly fat, mind you) and am now borderline overweight again. I’m eating 1800-2100 cals a day now (off season, too, so workouts are cut back) and I’m still having the same sugar issues. It’s been incredibly frustrating and has almost ruined running for me :(

        And yes, 2 is low but my doc told me that was good

        • I think blood sugar regulation issues and and an insulin level that low warrant another medical opinion. Perhaps an endocrinologist? I’m definitely out of my league here. :)

        • I don’t know about blood sugar per se– but I would definitely check out the Maffetone method– low heart rate running that relies on body fat so that you don’t ‘hit the wall’ or rely on gel packs. He’s trained some champion iron men and ultramarathoners. I’ve stepped back my workouts and am just doing low hr training and it has been a game changer for me. I was a HIIT kinda gal before, because I thought cardio was for losers (kinda joking) but I never saw my body transform and I started kind of hating the workouts. I don’t know if I have lost weight, but 6 weeks of doing walking (only about 3.2 on the treadmill b/c anything over that sends my heart rate too high– it’s kind of patheticly slow) and I’ve lost an inch around my thighs, 2 inches around my hips, and 1/2 an inch around the waist (it was not all that bad). I think it’s worth looking into for you.

          • Hi Susan. I played around with the Maffetone method a few years back but found it incredibly frustrating going that slow. Maybe it’s worth giving it another try. Thanks for the reply!

      • Yes, that was certainly the case at one point. I was eating 1500 cals a day and training for marathons and triathlons. However, for the past 2 years I’ve scaled back and have been eating more. I do get my period…but it’s on a very extended and erratic cycle. I just don’t understand what more I need to do to “recover” if that’s the case? And more importantly, I need to get these 10 pounds back off!

        • I have used this tool for nearly 3 years now to help me manage my training load and recovery:

          “ithlete ' New heart rate monitoring technology that tells you when to train and when to rest”

        • I think recovery is more important than the 10 pounds. Perspective. Your body may need that fat right now for endocrine health. An erratic period indicates an endocrine imbalance. Seriously, that’s a higher priority than your weight!

          So here’s another plug for seeing an endocrinologist. :)

  7. While I agree that being active helps insulin sensitivity, sugar does create an insulin response. Can you handle sugar better if you exercise? Of course. To me, this is a good reason to skip the sugar if you’re inactive.

    Both a lack of exercise and too much refined sugar has no doubt increased metabolic problems. If you’re in the “sugar is fine” camp so long as you exercise, why should anyone take you more serious than those you criticize? After all, the exercising can only make up for so much sugar consumption.

    I personally just did a personal experiment with nutritional ketosis. Prior I normally consumed avg of 2800 calories per day. 300 grams of carbs per day, maybe 100 grams of sugar. I averaged about 2.7 ketone level over 6 weeks, maintained same activity level and consumed avg of 4300 calories per day. I lost 10 pounds and went from 13% body fat to 9%. My TG went from 142 prior to ketosis to 74 my last week. Before this experiment was a huge proponent of energy in/ energy out, ad I call it. Obviously this a bit more complicated.

    Even if we all exercised we could eat all the sugar we want, I think it’s silly to be so dismissive of sugar. I mean, it seems clearly to be part of the problem. My wife’s an endocrinologist and told me that about 40% of the people she sees with metabolic issues are considered to be if healthy weight and have normal body fat%. A lot if thaws people exercise quite a bit as well…she tells stories all the time if avid endurance runners with diabetes to people who think it only plagues the obese.

    For many reasons, some people, regardless of exercise, don’t respond well to high carb loads. And when this occurs, sugar can be especially pernicious.

    • Read it again, Shep. I said exercise mitigates the insulin response to sugar.

      mit i gate
      / mit'?g t/

      -Make less severe, serious, or painful: “he wanted to mitigate misery in the world”.
      -Lessen the gravity of (an offense or mistake).

  8. LOVE your site!
    I do wonder if you have any information regarding “reactive” hypoglycemia and exercise. I began having issues with my blood sugar getting low about 18 months ago and have had numerous tests to check for everything from insulin producing tumors to diabetes and nothing so far except a vague daignosis of “reactive” hypoglycemia. I do not wake up with fasting low blood sugar but it will drop 2-3 hours after I eat so I eat every 2-3 hours and I eat carbs with protein and fat. I eat 1,800 calories a day which is maintenance for me. I’d like to lose some weight but I’m focusing on my blood sugar issues at this point. I used to lifting heavy but since last October (when I had what I am guessing was anxiety but thought was low blood sugar at the time) I have not worked out because of fear my blood sugar will drop. It seems everything I read is conflicting some say its good to exercise for low blood sugar others say exercise lowers blood sugar during and up to 24 hours after exercise. All of this has caused me to have anxiety because I am always fearful my blood sugar will drop. I just want to feel normal again. Any direction is greatly appreciated.

  9. Does the effect carry-over if one exercises every other day? Or does one have to exercise daily to reap these benefits? Is it just cardio that has this effect, or any exercise? (Like lifting or calisthenics?)

    • All/any exercise is beneficial, find something you enjoy. it doesn’t have to be every day, just consistent and regular. 3-4 timesa week, consistently, is probably adequate for most. I take two rest days a week. :)

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