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Exercising before a fasting blood test?
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Exercising before a fasting blood test?

Hi,

I just recently had a fasting blood test. That morning, about 3 hours before the test, I engaged in a 25 minute jog ( 5.5mph, as I do nearly every morning). Unfortunately, no one had informed me that I should abstain from exercise prior to bloodwork like this. So I'm wondering, how would exercise affect my results?

Of particular (though not exclusive) interest are the following:
-> Triglycerides (Total was 39. Normally it's around 50 for me, so this is an obvious improvement.)
-> Glucose (Total was 88. Last test done was 2 years ago, and was 79)
-----> Regarding the glucose: would the amounts be higher (due to the liver releasing sugars into the blood) or lower (due to the body's insulin response)?

I'm 32, 6'0, 220lbs. I have also started juicing a lot lately (over the past month), mostly vegetable juices flavored with apples and a lemon.

My biggest concern is insulin sensitivity: 2 years (and about 15lbs) ago I was diagnosed with flatline hypoglycemia (Results: Fasting: 79; 1hr: 81; 2hr: 71). I've since been working towards improving my insulin sensitivity.

Can I generally trust the result that I received (ie, it's under 99, so I'm OK), or was this blood test way skewed due to the exercise? Should I re-test?
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9 Comments Post a Comment
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1236893_tn?1408490528
I would retake the blood work! As it can effect the test!
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1829282_tn?1325595258
I'm confused how exercise can have an affect on a blood test... explain?

I thought this thread was going to be something along the lines of... should I exercise because I haven't eaten anything since the day before... not smart, btw.
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1236893_tn?1408490528
The University of Michigan Health System advises that exercise can result in either an increase or a decrease in blood sugar levels. During exercise, insulin becomes more efficient. This effect can persist, lowering blood sugar levels for hours afterward. An hour of afternoon exercise may lower glucose levels until the next morning, affecting the fasting blood sugar test. Exercise can also affect glucose levels by releasing adrenaline. This raises blood sugar temporarily. Physical exertion or other activities that cause excitement may increase fasting sugar levels if performed shortly before the test.


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Avatar_m_tn
Actually, that's how I do it every morning, taking a jog (usually 30 mins to 1 hr) before breakfast. On this particularity morning the run was as normal (a bit slower, actually), and for about 20 minutes. It was approximately 3 hours before the test. (Run ended at 6:45, test took place around 10am.)

Gymdandee
I had read that study as well, but what I wanted to know is, more specifically, approximately how many percentage (or total) points of a drop or rise are we talking about?

I doubt the result were too heavily affected either way (ie, I doubt I'm a diabetic, or even pre-diabetic) so I won't worry too much about it, and remember this for next time. If I find I keep thinking about it I'll pick up a cheap glucose monitor and test myself. No need to have the lab redo the test just for this.
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1236893_tn?1408490528
The percentage points varies to each individual!
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Avatar_f_tn
Last time I took a fasting glucose it was 99. Since then I've lost 20 lbs, started exercising, and eating super healthy (lots of fruits, veggies, protein, and healthy fats). And my most recent fasting glucose was 101! How can this be? I exercised about 1.5 hours before the test for an hour and it was very intense weight lifting. I hope the weight lifting is what caused that or else I am going on medication because I am doing everything anyone could do eating and activity wise. :(
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Avatar_m_tn
Exercising in a fasted state is actually smart.

Think about it from an evolutionary standpoint.  If you're an animal or a human living in a primal state, without access to supermarkets or refrigerated food, you go out to hunt or forage not when you've just eaten, but when you're hungry.

Intermittent Fasting (IF) is an approach to fitness which works well for many people.  I've fasted for 18-36 hours, twice a week, and waited until the end of that fast to do 20-30 minutes of high-intensity strength/interval workouts.  I do not do aerobic exercises, like running, as those can be counter-productive to dieting (increasing appetite) and don't increase muscle mass.  Increased muscles improves metabolism as they burn more calories, by weight.

I have skipped the workout when I don't feel up to it, but nearly all of the time, I do just fine lifting weights, doing lunges and sprints, without eating for about a day beforehand.  In a fasted state, the body kicks into high gear, burning fat like crazy.
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Avatar_m_tn
@epdiva125, I was prescribed Metformin for high A1C, even though my fasting glucose went from 122 to 86.  I was being strict for a couple weeks before the test, but the A1C is described as a 3-month average.

I chose not to take the Metformin.  Instead, I ate a very strict diet and exercised.  I dropped 35 pounds and felt amazingly better.

Before you consider taking medication, review your diet.  Are you eating grains?  Bread, cereal, etc.?  Are you eating much processed food, such as packaged foods in boxes, cans, or frozen dinners?  Fast food?  Many fruits contain significant amounts of sugar.  Are your "healthy fats" from vegetable oil/seed oil?  Those can often included way too much Omega-6, which can be bad, as opposed to Omega-3/Omega-9, which are healthy.  Don't believe that saturated fat from meat and dairy is, in and of itself, "unhealthy".  Ancel Keys fabricated his research in the 1950s and the medical, nutritional, and government establishments have promulgated the bad information behind his lipid hypothesis.

Foods which are labeled as "diet", "low fat", "heart healthy", etc. usually replace the allegedly bad ingredients with something else which is just as bad, if not worse.  For example, take out the fat and add high fructose corn syrup, which gets stored as fat and which plays havoc with the glucose/insulin.  Take out the sugar and add artificial sweeteners which increase appetite.

Try to get your nutrition from whole foods.  Lots of green leafy vegetables.  A moderate amount of meat (grass-fed, organic if you can afford it).  Avoid processed meats like lunch meat and hot dogs.  Avoid corn and white potatoes.  Don't eat wheat (bread, pasta, pizza, etc.).  Eat small amounts of raw, unsweetened fruit and avoid those fruits which have a high glycemic index (GI)/glycemic load (GL).  Limit the amount of nuts you eat (a handful a day, at most).

A healthy diet will contain a good balance of calories from carbs, protein, and fat.  A low-carb diet can be OK for a short period, but dieters often get too much protein, which can make weight loss difficult.  It's more important to carefully choose your sources of carbs.  Cutting out protein or fat can be detrimental.  Fat, of course, is more dense, so it takes less, by weight, to give you the same calories as protein or carbs.
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Avatar_f_tn
This is a very unhealthy and detrimental exercise routine. When you are fasting for greater than 18 hours your body breaks down muscle and then goes into what is called gluconeogenesis. This metabolic pathway is highly inefficient. If you are trying to build muscle, I think you might want to consider fasting at most for 12 hours. Also aerobic exercise is NOT counter-productive for weight loss, but unsustainable for fasting >18 hours. We must eat to live, and our body needs valuable macro and micro nutrients to sustain life. Moderation and balance is key to living a healthy life.
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