Insulin gets a bad rap, but it's simply a hormone the body makes in response to the food we eat. It can either help us store the energy we get from food in muscle cells (good) or in fat cells (not good).
The more muscle you have – and the more insulin sensitive that muscle is – the greater capacity you'll have to store muscle glycogen. Ideally, you'll store more of what you eat as muscle while also getting leaner, i.e. reducing the amount of fat you're storing. Impossible? Nope, you can change your body composition by changing your insulin sensitivity. And you can change your insulin sensitivity with these three tools.
Insulin regulates our metabolism and is released in greatest amounts when we eat. This is to our benefit depending on when, what, and how we're eating.
Some think that avoiding carbs is the key to leanness, but cutting them altogether makes muscle glycogen synthesis more difficult. And if you play sports or care about your lifting performance, then it'll keep you from maximizing your potential. Carbs are a fast acting bioenergetic fuel source. Sure, an unnecessarily high carb intake throughout the day isn't without consequence. It may even make you more insulin resistant depending on how excessive it is. Instead, consume the majority of your carbs around the time of your workout when you'll need and use them most.
Get Adequate Fiber, But Not Around Workouts
Increased fiber intake has been shown to have blood glucose lowering effects and may increase total body insulin sensitivity. The only caveat? Don't have your high fiber meal around workout time. That's when you'd want to have a greater insulin spike so that your workout nutrition can be directed to your muscle cells.
Multiple studies have shown that faster eaters are also more insulin resistant. These studies even accounted for factors like genetic predisposition, BMI, caloric intake, waist circumference, and triglyceride levels. Fast eating has been linked with obesity and it's believed that speed eating makes it more difficult for your appetite suppressing hormones to take effect, which ultimately affects insulin's ability to do its job.
Exercise is the antidote for raising insulin sensitivity in muscle cells. Studies show that a single workout can increase your insulin sensitivity for at least 16 hours post training. Both strength training and conditioning have been shown to make significant improvements to our insulin sensitivity in a short amount of time.
Strength Training: Researchers have found that both insulin sensitivity and glucose uptake capacity in muscles increases with resistance training. Storing glycogen in the muscle cells is a gift that keeps on giving. As you train, you use your muscles, they use up the glycogen, you burn more total calories, and then when you eat you replace that depleted glycogen with more energy for later use.
Add some glycogen-depleting finishers to your normal strength training:
- Timed kettlebell swings, snatches, & clean and jerks
- CrossFit WODs
- Circuit training
- AMRAP (as many reps as possible) bodyweight exercises
Conditioning: Both long, slow cardio and fast, intense cardio have their place in improving insulin sensitivity. And the improvements come quickly. One study showed that just two weeks of high intensity exercise (4-6 sets of 30 second sprints) made subjects significantly improve their insulin sensitivity.
Researchers have found that aerobic exercise (in the zone-2 cardio range, 65-75 percent of VO2 Max) has been shown to improve insulin sensitivity. Their studies show that this happened through the activation of AMPK (AMP activated protein kinase), an enzyme involved in glucose and lipid metabolism. Likewise, high intensity exercise (greater than 80 percent of VO2 max) has been shown to improve insulin sensitivity and lower blood glucose for up to 1-3 days post exercise.
Try intervals with these for a high intensity insulin sensitivity boosting workout. Incorporate 5 sets of 30 second intervals a few times a week into your program.
- Hill sprints
- Prowler pushes
- Jump rope
- Rowing ergometer
- Battling ropes
You can also improve insulin sensitivity with proper supplementation. Although these substances can be found in food sources, it's easier to get a potent and condensed source from supplementing. In fact, you may not even get the benefits without using a concentrated supplement.
C3G comes from a powerful chemical from nature called anthocyanin. It's found in dark blue to purple colored fruits and vegetables (like blackberries, boysenberries, purple carrots, and purple yams). C3G improves insulin sensitivity by increasing the upregulation of GLUT4 glucose transporters and down regulating "Retinol Binding Protein 4" which is an adipokine called RBP4 that's associated with increasing insulin resistance in white adipose tissues. Insulin sensitivity of muscle cells increases, thereby enhancing insulin signaling and glucose and nutrient uptake, along with enhancing glycogen synthesis, which drives glucose and nutrients preferentially into muscle. C3G up-regulates gene expression for fat oxidation (fat burning) and down-regulates gene expression for fat storage.
Conjugated Linolenic Acid (CLA)
CLA is a fatty acid found in meat and dairy sources, especially higher quality beef, milk, and eggs. Supplementing with 3 grams of CLA over an eight week period can improve insulin sensitivity and positively affect glucose metabolism.
Fish oil oxidizes into a fatty acid that activates PPAR, a molecular sensor that plays roles in carbohydrate and lipid metabolism. Activation of PPARs increases the burning of fatty acids and improves their insulin sensitivity. Studies involving mice have shown that fish oil administration can increase adiponectin levels which work through PPAR receptors in epididymal fat in as little as 15 days. A systematic review and meta-analysis found that a dose of 1.3 grams daily of fish oil over the course of 8 weeks was enough to increase circulating adiponectin levels.
- Otsuka R et al. Eating fast leads to insulin resistance: Findings in middle-aged Japanese men and women. Prev Med. 2008 Feb;46(2):154-9.
- Borghouts L et al. Exercise and Insulin Sensitivity: A Review. Int J Sports Med. 2000 Jan;21(1):1-12.
- Hansen E et al. Insulin Sensitivity After Maximal and Endurance Resistance Training. J Strength Cond Res. 2012 Feb;26(2):327-34.
- Whyte L et al. Effect of 2 weeks of sprint interval training on health-related outcomes in sedentary overweight/obese men. Metabolism. 2010 Oct;59(10):1421-8.
- Moloney F et al. Conjugated linoleic acid supplementation, insulin sensitivity, and lipoprotein metabolism in patients with type 2 diabetes mellitus. Am J Clin Nutr. 2004 Oct;80(4):887-95.
- Sasaki R et al. Cyanidin 3-glucoside ameliorates hyperglycemia and insulin sensitivity due to downregulation of retinol binding protein 4 expression in diabetic mice. Biochemical Pharmacology. 2007 Dec;74(11):1619-1627.
- Neschen S et al. (2006) Fish Oil Regulates Adiponectin Secretion by a Peroxisome Proliferator-Activated Receptor-Dependent Mechanism in Mice. Diabetes. 2006 Apr;55(4):924-8.
- Wu JHY et al. Effect of fish oil on circulating adiponectin: a systematic review and meta-analysis of randomized controlled trials. J Clinical Endocrinol Metab. 2013;98(6):2451-2459.