The science behind blood sugar and how fiber can impact the way energy is stored. More fiber and less sugar is the prescription for metabolic control. Some practical advice on how to increase fiber is provided at the end.
The science behind blood sugar and how fiber can impact the way energy is stored and used in the body.
Part 1 of this series focused on how appetite and nutrient absorption in the gut impact weight loss. To recap, the most powerful approaches to weight loss, including the drug GLP-1 and bariatric surgery, change the energy account balance and reset the metabolism set points. They both decrease appetite through hormones (less calories in), and in the case of surgery, increase the calories that don’t get absorbed (more calories out). The good news is that consuming more fiber in our diets can be used as a complementary approach to weight loss as it decreases appetite through the same GLP-1 hormone pathway (less calories in) and makes food harder to digest (more calories out).[2,3]
But you might ask, what about ketogenic diets, intermittent fasting, non dietary approaches, and new high-tech personalized approaches to weight loss? Are these effective, how do they work, and how might fiber be a complement to these approaches? The common thread to all these weight loss measures is how blood sugar levels control the use (or storage) of calories inside the body. It turns out fiber also has a role to play here. Here’s how in a bite-sized overview of a feast-sized field.
Keto: craze or credible?
The ketogenic diet aims to keep blood glucose levels very low by having you avoid eating carbohydrates and foods that have low or no glycemic index (fats and proteins). The glycemic index refers to just how quickly and strongly various foods raise the sugar levels in your blood. The higher these levels go, the more dramatically they stimulate insulin levels. Insulin is a hormone that, among other jobs, helps convert excess sugar to fatty acids that are stored largely in fat and liver cells. Higher blood sugar leads to higher insulin levels, which leads to more fat.
A ketogenic diet keeps blood sugars low so your body has less access to this energy type. Your body instead taps into dietary and body fat to fuel itself. When fat is converted to energy, it creates ketone bodies. Unlike calorie restrictive diets that can make you more hungry, ketones actually help control your appetite so you eat less food (less calories in), and help maintain your body’s metabolic rate by preserving muscle over fat (calories burned). The end result? You decrease fat in the body and lose weight. The data looks promising for ketogenic diets and some companies (e.g. Virta Health) are tapping into this powerful approach![10,11] There are some great resources on the web providing advice on how to follow a lower carbohydrate diet (e.g. Dr. Lori Shemek)
Of course, there remain questions as to how sustainable this diet might be in the long run. There are also unresolved questions around whether a high fat diet might lead to high cholesterol and cardiovascular disease while a high protein diet might lead to stress on the kidneys in the long run.[13,14] A diet that balances higher amounts of plant-based fat and protein with lower amounts of animal-based nutrients may help prevent the potential long term risks of a ketogenic diet and be superior for health.[15,16] Also there might be important lessons from traditional hunter gatherer societies that have alternating wet and dry seasons with alternating high carbohydrate (berry and honey) and high protein (bush meat) diets.
In excluding sugar and carbohydrates, it is also essential to not lose sight of the importance of fiber, which has very synergistic benefits with a keto diet. It is notable that fiber consumption (baobab fruit and tubers) remains constant across all seasons in hunter gatherer societies. Indeed, the butyrate made from fiber by the gut microbiome and the beta-hydroxybuturate (a ketone) made from fat in a keto diet, work in much the same way to control appetite, decrease blood sugar, and preserve muscle!(See blog on butyrate) It is also important to note that fiber helps prevent constipation that is often associated with keto diets and may help prevent the long-term risks of colon, breast and prostate cancer associated with a low fiber diet.[19–21]
Intermittent fasting: proselytized or promising?
So what about intermittent fasting, a group of several different diets that restrict eating to only some days of the week or hours of the day? (For practical advice on fasting and a discussion of different protocols, Beginners Guide to Intermittent Fasting.) This works in a very similar way to a keto diet but rather than an around-the-clock depletion of sugar from the blood, it intermittently triggers the body to use fat reserves instead of sugar. The end result is similar – a decrease in fat and improved weight loss.[22,23] Some think that a diet like this is more sustainable than a ketogenic diet because the rest of the time you can still consume a ‘regular diet’. This can be less socially limiting if you want to go out for a meal with friends and family.
The relative downside of intermittent fasting is that weight loss might be less dramatic than in a stricter ketogenic diet and some (although not all) studies have shown that it may contribute to muscle loss in certain settings. Intermittent fasting in the setting of a high fiber diet might help mitigate against muscle loss as fiber and the molecules it stimulates (butyrate and GLP-1) have been shown to help prevent muscle wasting.[25,26]
Staples beyond diet: exercise, stress reduction, and sleep
So what about weight loss measures beyond diet: exercise, stress reduction and sleep? It turns out all of these activities have direct effects on blood sugar as well and this is likely one major way they benefit weight loss. How? Exercise funnels blood glucose into muscle cells to burn instead of fat cells to store. Exercise is especially useful within 15 minutes of a meal to help prevent spikes in glucose and insulin! Good sleep (aim for 8 hours per night) and stress reduction decrease your body’s production of natural steroids like cortisol that can increase appetite, blood sugar levels, insulin and fat![29,30]
New horizons in personalized blood sugar control
The new kids on the block in weight loss are continuous glucose monitors (e.g. Dexcom and Abbott). Originally developed for folks with diabetes, they provide a near real-time assessment of sugar levels in the blood to alert someone to make an immediate modification to diet and lifestyle factors. While currently only available for those with diabetes through a prescription from their doctor, there is a lot of excitement to potentially one day soon use these devices in folks that don’t have diabetes. Research is underway as to its usefulness and a number of companies (e.g. Levels Health) are banking on its success.
Other companies (e.g. DayTwo and Zoe) have correlated specific stool microbiome signatures with blood sugar responses and make recommendations for eating based on a stool test. These personalized approaches to blood sugar control and weight loss could be game changers because it turns out that everyone’s response to foods in their blood sugar levels is different. Having real-time feedback could be invaluable for helping people choose the right foods!
We all need fiber, fast!
This brings us full circle to fiber. There is growing evidence that elevated blood sugar levels, rising obesity, and rising rates of diabetes may not arise only from consuming too much sugar and refined grains.[33,34] The lack of fiber might be just as important. Simple carbohydrates in nature are normally packaged part and parcel with fiber which naturally prevents the rise in blood sugar levels.
In the stomach, some fibers (e.g. beta glucan) form a gel that traps sugar and slows its release to the small intestine. In the small intestine, some fibers (e.g. beta glucan) can decrease the transporters in the cells and gaps between the cells to decrease sugar absorption.[38,39] That’s a good thing! In the colon, some fibers (e.g. resistant starch and beta glucan) are transformed by the microbiome into butyrate, which stimulates the colon cells to make the GLP-1 hormone.[40,41] GLP-1 signals fullness and regulates appetite as discussed in Part 1, but also regulates how much insulin is being produced by the pancreas and how well muscles take up sugar to use it for energy.
So to summarize it is important to limit sugar, but it’s also important to increase fiber. The fiber-to-carbohydrate ratio has been touted by some as a better metric of how much sugar and fiber to consume and has been associated with lower blood glucose and weight. Aiming for foods or food combos that have a ratio of greater than 10 grams of sugar to 1 gram of fiber is great and a ratio of 5 grams of sugar to 1 gram of fiber might be golden. Low FODMAP fiber supplements can also be helpful in reaching the recommended 30g of fiber a day. At the end of the day, consider fiber is a powerful and empowering complement to other blood sugar centric strategies for weight loss! (See blog on fiber)
More Articles & Resources
If you enjoyed this article, please feel free to visit gutbites.org where you’ll find more practical food and microbiome digests to improve gut health and lift your whole self! Would love to hear your comments below too!
1. Quercia I, Dutia R, Kotler DP, Belsley S, Laferrère B. Gastrointestinal changes after bariatric surgery. Diabetes Metab. 2014;40: 87–94. doi:10.1016/j.diabet.2013.11.003
2. Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol . 2020;11: 25. doi:10.3389/fendo.2020.00025
3. Qi X, Al-Ghazzewi FH, Tester RF. Dietary fiber, gastric emptying, and carbohydrate digestion: A mini‐review. Starke. 2018;70: 1700346. doi:10.1002/star.201700346
4. Abbasi J. Interest in the Ketogenic Diet Grows for Weight Loss and Type 2 Diabetes. JAMA. 2018;319: 215–217. doi:10.1001/jama.2017.20639
5. Augustin LS, Franceschi S, Jenkins DJA, Kendall CWC, La Vecchia C. Glycemic index in chronic disease: a review. Eur J Clin Nutr. 2002;56: 1049–1071. doi:10.1038/sj.ejcn.1601454
6. Dimitriadis G, Mitrou P, Lambadiari V, Maratou E, Raptis SA. Insulin effects in muscle and adipose tissue. Diabetes Res Clin Pract. 2011;93 Suppl 1: S52–9. doi:10.1016/S0168-8227(11)70014-6
7. Roekenes J, Martins C. Ketogenic diets and appetite regulation. Curr Opin Clin Nutr Metab Care. 2021;24: 359–363. doi:10.1097/MCO.0000000000000760
8. Parker BA, Walton CM, Carr ST, Andrus JL, Cheung ECK, Duplisea MJ, et al. β-Hydroxybutyrate Elicits Favorable Mitochondrial Changes in Skeletal Muscle. Int J Mol Sci. 2018;19. doi:10.3390/ijms19082247
9. Gomez-Arbelaez D, Crujeiras AB, Castro AI, Martinez-Olmos MA, Canton A, Ordoñez-Mayan L, et al. Resting metabolic rate of obese patients under very low calorie ketogenic diet. Nutr Metab . 2018;15: 18. doi:10.1186/s12986-018-0249-z
10. Strombotne KL, Lum J, Ndugga NJ, Utech AE, Pizer SD, Frakt AB, et al. Effectiveness of a ketogenic diet and virtual coaching intervention for patients with diabetes: A difference-in-differences analysis. Diabetes Obes Metab. 2021;23: 2643–2650. doi:10.1111/dom.14515
11. Ludwig DS. The Ketogenic Diet: Evidence for Optimism but High-Quality Research Needed. J Nutr. 2020;150: 1354–1359. doi:10.1093/jn/nxz308
12. O’Neill B, Raggi P. The ketogenic diet: Pros and cons. Atherosclerosis. 2020;292: 119–126. doi:10.1016/j.atherosclerosis.2019.11.021
13. Kosinski C, Jornayvaz FR. Effects of Ketogenic Diets on Cardiovascular Risk Factors: Evidence from Animal and Human Studies. Nutrients. 2017;9. doi:10.3390/nu9050517
14. Crosby L, Davis B, Joshi S, Jardine M, Paul J, Neola M, et al. Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks. Front Nutr. 2021;8: 702802. doi:10.3389/fnut.2021.702802
15. Nestle M. Animal v. plant foods in human diets and health: is the historical record unequivocal? Proc Nutr Soc. 1999;58: 211–218. doi:10.1017/s0029665199000300
16. Seidelmann SB, Claggett B, Cheng S, Henglin M, Shah A, Steffen LM, et al. Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis. Lancet Public Health. 2018;3: e419–e428. doi:10.1016/S2468-2667(18)30135-X
17. Smits SA, Leach J, Sonnenburg ED, Gonzalez CG, Lichtman JS, Reid G, et al. Seasonal cycling in the gut microbiome of the Hadza hunter-gatherers of Tanzania. Science. 2017;357: 802–806. doi:10.1126/science.aan4834
18. Cavaleri F, Bashar E. Potential Synergies of β-Hydroxybutyrate and Butyrate on the Modulation of Metabolism, Inflammation, Cognition, and General Health. J Nutr Metab. 2018;2018: 7195760. doi:10.1155/2018/7195760
19. Hullings AG, Sinha R, Liao LM, Freedman ND, Graubard BI, Loftfield E. Whole grain and dietary fiber intake and risk of colorectal cancer in the NIH-AARP Diet and Health Study cohort. Am J Clin Nutr. 2020;112: 603–612. doi:10.1093/ajcn/nqaa161
20. Farvid MS, Spence ND, Holmes MD, Barnett JB. Fiber consumption and breast cancer incidence: A systematic review and meta-analysis of prospective studies. Cancer. 2020;126: 3061–3075. doi:10.1002/cncr.32816
21. Tabung F, Steck SE, Su LJ, Mohler JL, Fontham ETH, Bensen JT, et al. Intake of grains and dietary fiber and prostate cancer aggressiveness by race. Prostate Cancer. 2012;2012: 323296. doi:10.1155/2012/323296
22. Nowosad K, Sujka M. Effect of Various Types of Intermittent Fasting (IF) on Weight Loss and Improvement of Diabetic Parameters in Human. Curr Nutr Rep. 2021;10: 146–154. doi:10.1007/s13668-021-00353-5
23. de Cabo R, Mattson MP. Effects of Intermittent Fasting on Health, Aging, and Disease. N Engl J Med. 2019;381: 2541–2551. doi:10.1056/NEJMra1905136
24. Williamson E, Moore DR. A Muscle-Centric Perspective on Intermittent Fasting: A Suboptimal Dietary Strategy for Supporting Muscle Protein Remodeling and Muscle Mass? Front Nutr. 2021;8: 640621. doi:10.3389/fnut.2021.640621
25. Frampton J, Murphy KG, Frost G, Chambers ES. Higher dietary fibre intake is associated with increased skeletal muscle mass and strength in adults aged 40 years and older. J Cachexia Sarcopenia Muscle. 2021;12: 2134–2144. doi:10.1002/jcsm.12820
26. Hong Y, Lee JH, Jeong KW, Choi CS, Jun H-S. Amelioration of muscle wasting by glucagon-like peptide-1 receptor agonist in muscle atrophy. J Cachexia Sarcopenia Muscle. 2019;10: 903–918. doi:10.1002/jcsm.12434
27. Kang J, Robertson RJ, Hagberg JM, Kelley DE, Goss FL, DaSilva SG, et al. Effect of exercise intensity on glucose and insulin metabolism in obese individuals and obese NIDDM patients. Diabetes Care. 1996;19: 341–349. doi:10.2337/diacare.19.4.341
28. Reynolds AN, Venn BJ. The Timing of Activity after Eating Affects the Glycaemic Response of Healthy Adults: A Randomised Controlled Trial. Nutrients. 2018;10. doi:10.3390/nu10111743
29. Boudry G, Cheeseman CI, Perdue MH. Psychological stress impairs Na+-dependent glucose absorption and increases GLUT2 expression in the rat jejunal brush-border membrane. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 2007 [cited 22 Apr 2022]. doi:10.1152/ajpregu.00655.2006
30. Geiker NRW, Astrup A, Hjorth MF, Sjödin A, Pijls L, Markus CR. Does stress influence sleep patterns, food intake, weight gain, abdominal obesity and weight loss interventions and vice versa? Obes Rev. 2018;19: 81–97. doi:10.1111/obr.12603
31. Vidmar AP, Naguib M, Raymond JK, Salvy SJ, Hegedus E, Wee CP, et al. Time-Limited Eating and Continuous Glucose Monitoring in Adolescents with Obesity: A Pilot Study. Nutrients. 2021;13. doi:10.3390/nu13113697
32. Funtanilla VD, Candidate P, Caliendo T, Hilas O. Continuous Glucose Monitoring: A Review of Available Systems. P T. 2019;44: 550–553. Available: https://www.ncbi.nlm.nih.gov/pubmed/31485150
33. Aune D, Norat T, Romundstad P, Vatten LJ. Whole grain and refined grain consumption and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of cohort studies. Eur J Epidemiol. 2013;28: 845–858. doi:10.1007/s10654-013-9852-5
34. Rippe JM, Angelopoulos TJ. Relationship between Added Sugars Consumption and Chronic Disease Risk Factors: Current Understanding. Nutrients. 2016;8. doi:10.3390/nu8110697
35. Sawicki CM, Lichtenstein AH, Rogers GT, Jacques PF, Ma J, Saltzman E, et al. Comparison of Indices of Carbohydrate Quality and Food Sources of Dietary Fiber on Longitudinal Changes in Waist Circumference in the Framingham Offspring Cohort. Nutrients. 2021;13. doi:10.3390/nu13030997
36. Thompson SV, Hannon BA, An R, Holscher HD. Effects of isolated soluble fiber supplementation on body weight, glycemia, and insulinemia in adults with overweight and obesity: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2017;106: 1514–1528. doi:10.3945/ajcn.117.163246
37. Panahi S, Ezatagha A, Temelli F, Vasanthan T, Vuksan V. Beta-glucan from two sources of oat concentrates affect postprandial glycemia in relation to the level of viscosity. J Am Coll Nutr. 2007;26: 639–644. doi:10.1080/07315724.2007.10719641
38. Abbasi NN, Purslow PP, Tosh SM, Bakovic M. Oat β-glucan depresses SGLT1- and GLUT2-mediated glucose transport in intestinal epithelial cells (IEC-6). Nutr Res. 2016;36: 541–552. doi:10.1016/j.nutres.2016.02.004
39. Merino B, Fernández-Díaz CM, Cózar-Castellano I, Perdomo G. Intestinal Fructose and Glucose Metabolism in Health and Disease. Nutrients. 2019;12. doi:10.3390/nu12010094
40. Zhao L, Zhang F, Ding X, Wu G, Lam YY, Wang X, et al. Gut bacteria selectively promoted by dietary fibers alleviate type 2 diabetes. Science. 2018;359: 1151–1156. doi:10.1126/science.aao5774
41. Zhou J, Martin RJ, Raggio AM, Shen L, McCutcheon K, Keenan MJ. The importance of GLP-1 and PYY in resistant starch’s effect on body fat in mice. Mol Nutr Food Res. 2015;59: 1000–1003. doi:10.1002/mnfr.201400904
42. Hinnen D. Glucagon-Like Peptide 1 Receptor Agonists for Type 2 Diabetes. Diabetes Spectr. 2017;30: 202–210. doi:10.2337/ds16-0026
43. Comerford KB, Papanikolaou Y, Jones JM, Rodriguez J, Slavin J, Angadi S, et al. Toward an Evidence-Based Definition and Classification of Carbohydrate Food Quality: An Expert Panel Report. Nutrients. 2021;13. doi:10.3390/nu13082667
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