Your Six Pack Might be Ruining Your Health. How Lean is Too Lean?

We all know the narrative of the couch potato with excessive weight gain and high blood sugar. Blood glucose increases with a combination of inactivity and insulin resistance. We generalize this as unhealthy. But what about the inverse? Could eating a low-carb Paleo diet and practicing metabolically challenging exercise result in excess leanness or low blood sugar? Can your six pack be killing you?

Simply asked, can you be too lean?

The answer, of course, is yes…sometimes. The trouble is that it’s rarely black and white. Through interval training and a low-carb, hypocaloric diet, your body will move away from insulin resistance and high blood sugar, and move toward healthier insulin sensitivity. It all results in a body that is leaner, carries lower circulating blood sugar, and requires less insulin—the hormone that signals storage and preservation of calories. This is good—you will be leaner, your circulating fats (as triglycerides) will be reduced, your insulin will lower and you will experience lower overall blood sugar.

But too much of a good thing is too much. Endurance athletes are a great example of this. With high training frequency and long-duration exercise, perhaps greater than two hours at a time, insulin sensitivity can be overly expressed. This results in crashes in blood sugar (hypoglycemia) and/or excessive weight loss – and I’m not talking about fat loss. I’m talking precious lean tissue – muscles, bones, and more.

Let me explain how you can look for this and what it all means.

Blood Testing and Biomarkers to Track

First, check the following tests from the Blood Code Metabolic Discovery Panel.

  • HgbA1c: should be 5.2-5.7% in athletes. If HgbA1c is <5.1% this indicates blood sugar is dipping low, perhaps below 65-70 mg/dL.
  • Fasting Blood Sugar (glucose): 75-95. At levels lower than 75, I suspect that episodes of hypoglycemia are occurring.
  • Serum Insulin: between 3-8 uIU/mL. If is is low, below 2.0 uIU/mL, finessing higher carbohydrates into the diet can assist recovery and anabolic effect.
  • Triglyceride / HDL ratio: A healthy ratio is 0.5-1.5. I expect athletes to be in the metabolically lean 0.5-1.0 range. But below 0.5, there may be inadequate triglyceride to provide energy during fasted exercise.
  • I also check Ferritin (which is not just a storage form of iron, but a hormone-like compound in muscles) and B12. Low levels of either compromise recovery.

A word about blood sugar testing, and how to double check HgbA1c:

If HgbA1c is high or low, you can look closer at daytime glucose readings. I personally use the old-school, simple Bayer Contour. I will be checking out the continuous glucose monitors (CGM) in the next months, but for now – I recommend the following: Do a glucose check about SIX times in one day, with a diet and fitness log on that same day. This gives a nice visual of what is happening with circulating glucose pre and post meals, and after a couple months, you’ll gather enough data days to see trends. In my clinical experience, what feels like hypoglycemia to people is usually not low blood sugar.

TOO Lean Defined:

  • Triglyceride: <40 mg/dL (<0.45mmol/L)
  • TG:HDL (as mg/dL) ratio <0.5
  • Low Body Fat percentage: Under 10% for men and, under 15% for women

Low Blood Sugar/Hypoglycemia Defined:

  • HgbA1C of <5.1% (<32mmol/mol)
  • Fasting blood glucose <75 mg/dL (<4.2mmol/L)
  • Any daytime blood sugar <70 mg/dL (<3.9mmol/L).

What to Do if You’re Too Lean

Prioritize recovery. Your body requires adequate recovery time between bouts of training, adequate protein intake to recover from tissue damage, and a healthy replenishment of the storage sugars (glycogen) back into the liver and muscles. Your reserve of fat calories is relatively low when triglycerides are low in the bloodstream and tissue body fat percentage is low. We love that metabolically demanding exercise in a modified fasted state plus and a low-carb-high-fat diet effectively make us more fat-adapted, allowing preferential burn of fats for energy. But with a limited bank account of fats to draw upon, your body will need alternate energy sources. It is true, in my experience, that men tolerate this state better than women. And I believe it is due to the overall higher muscle mass that allows more glycogen storage, thereby preventing a caloric or glycemic crash.

A low carb Paleo diet will certainly help you become leaner and more insulin sensitive, but for the best recovery, some healthy carbohydrates may need to be added into the diet to support and recover from sustained activity. Sweet potato, any root vegetables, winter squashes, and even some properly prepared pulses/legumes are great ways to get these starchy carbs into your diet. Personally, I am not a big guy, and when my body goes below 10% body fat, I lose power and strength and get sick if I push any harder. I do not feel ‘tired” at this low body fat, because adrenaline releases to keep my blood sugar stable—the resultant emotional state is anxiousness. I increase my protein and carbohydrate intake, and adjust my activity to provide better recovery time, which allows my body fat percentage to reach 11% or 12%. This sounds like a small change, but it’s a 20% increase and makes a huge difference.

So, don’t be afraid to increase your carbohydrates, your time between workouts, and let your body fat creep up a little bit. It might sound counterintuitive, but it’ll do great things for your health and performance.

What to Do if You Have Low Blood Sugar

Let me first clarify that I find this to be rare, especially if you follow a Paleo or LCHF diet. If I look at the past ten clients where hypoglycemia was confirmed, eight of them were women short stature, under 5’5”, and not muscularly developed. They did not have adequate muscle mass to provide glycogen storage. In these cases, I emphasize higher dietary fat and “slow” fibrous meals to trickle absorption of carbohydrate.

The other two-out-of-ten cases had low blood sugar due to prescription drug intake. Opiate and Narcotic pain medications, stimulant drugs and diabetic hypoglycemic medications all play and obvious role in hypoglycemia. But other medication side effects are updated regularly, so seek out an inquisitive healthcare provider to look in this direction if suspect.

I believe blood tests are a necessary step to see how your diet, metabolic tendencies and fitness interact. Myself personally, I tend toward high blood sugar (pre-diabetes) and have a strong family history of type 2 diabetes. This means I can eat very low-carb and exercise on an empty stomach for hours and brilliantly remain normoglycemic. In fact, at fifty years of age, I can’t get hypoglycemic if I tried. I view my tendency toward insulin resistance as a magical trait that allows extended activity without food while maintaining adequate glucose to fuel my brain. But don’t do as I do. Run some blood tests and make some changes. Discover what your body needs to find glycemic balance and perfection within your optimal lean.

Six Pack Abs photo licensed under the Creative Commons.

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Dr. Richard Maurer

Dr. Richard Maurer, author of The Blood Code: Unlock the Secrets of Your Metabolism (Early 2014), has practiced integrative medicine in Maine since 1994.

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