Research published this February 2024 in Nature Metabolism [2] sheds light on a potential pathway for weight loss and improved metabolic health: resistant starch (RS) and its impact on the gut microbiome. This blog post dives into the details of the study, exploring how RS consumption might help individuals with weight management and promote metabolic flexibility.
What is Resistant Starch (RS) and How Does it Benefit Metabolic Health?
Unlike regular starch, RS escapes digestion in the small intestine and reaches the colon largely intact. It acts as a prebiotic in the colon, feeding specific beneficial gut bacteria. Researchers and health professionals are intrigued by this unique property of RS's potential health benefits, including weight loss and improved metabolic health. Here's how RS may benefit your metabolic health according to research:
Reduced inflammation: Studies suggest that RS can help reduce chronic inflammation in the body, a critical factor in various metabolic disorders like diabetes and cardiovascular disease [3, 4].
Improved blood sugar control: By promoting the growth of beneficial gut bacteria, RS may improve insulin sensitivity and help regulate blood sugar levels [5].
Enhanced satiety: Some studies suggest that RS can promote feelings of fullness and reduce appetite, potentially leading to decreased calorie intake and aiding weight management [6].
What is Metabolic Flexibility and How Does RS Play a Role?
Metabolic flexibility refers to the body's ability to switch between different fuel sources (glucose and fatty acids) efficiently according to its needs. In a state of good metabolic flexibility, the body can readily use glucose for immediate energy during periods of high activity and switch to burning fat for fuel during periods of fasting or rest.
Emerging research suggests RS may promote metabolic flexibility by influencing the gut microbiome [7]. Studies show that RS can increase the abundance of beneficial gut bacteria associated with improved metabolic health [8]. These bacteria are believed to play a role in:
Enhancing insulin sensitivity: This allows the body to utilise glucose more effectively, potentially reducing reliance on stored fat for energy [9].
Improving fat metabolism: Certain gut bacteria can influence how the body stores and utilises fatty acids, potentially leading to increased fat burning for energy [10].
While the research on the exact mechanisms is ongoing, these findings suggest that RS may contribute to improved metabolic flexibility, offering benefits beyond weight loss.
The Study: Resistant Starch, Weight Loss, and Gut Microbiome Changes
The study published in Nature Metabolism [2] involved 37 individuals with overweight or obesity. Researchers divided up two groups: one receiving a daily supplement of RS for eight weeks and the other receiving a placebo. The results were promising:
Weight Loss: The RS group experienced an average weight loss of 2.8 kg (around 6.2 lbs) compared to the placebo group.
Improved Insulin Sensitivity: The RS group also showed improved insulin sensitivity, suggesting better blood sugar regulation.
Gut Microbiome Changes: Interestingly, the study linked the weight loss benefits to changes in the gut microbiome composition of the RS group.
How to Increase Resistant Starch in Your Diet
You can increase the amount of resistant starch present in certain foods by following specific methods:
1. Cooking and Cooling: This is the most common and accessible way to increase resistant starch content. Simply cook and then cool starchy foods like:
Rice: Cook rice as usual, then refrigerate for at least 12 hours before consumption or reheating [11].
Potatoes: Boil or bake potatoes, then refrigerate for at least 12 hours before consumption/reheating [11].
Pasta: Cook pasta according to package instructions, then refrigerate completely before consuming or reheating [11].
Beans and lentils: Cook beans or lentils as usual and allow them to cool completely before consuming or reheating [11].
2. Using Certain Flours: These flours naturally contain higher levels of resistant starch compared to traditional wheat flour:
Green banana flour: Made from unripe bananas, it has a distinct flavour and is high in resistant starch.
Plantain flour: Similar to green banana flour, it is made from unripe plantains and offers a higher resistant starch content with a neutral flavour.
Cassava flour: Made from cassava root, it provides a good source of resistant starch but requires careful preparation due to a naturally occurring toxin.
3. Consuming Certain Foods Raw: Some foods naturally contain higher levels of resistant starch when eaten raw or undercooked:
Green bananas: As they ripen, the resistant starch content decreases significantly [12].
Oats: Rolled oats contain more resistant starch than quick oats or cooked oats. Soaking raw oats in yoghurt or milk overnight (overnight oats) can further increase resistant starch content.
Remember, while increasing resistant starch intake can be beneficial, it's crucial to introduce it gradually to avoid potential side effects like bloating and gas. It's also important to consult a healthcare professional before making significant dietary changes, especially for individuals with underlying medical conditions.
References
Cani PD, et al. Gut microbiota modulation alters metabolism and endocrine functions and reveals bedtime as an optimal window of opportunity for dietary interventions. Cell Metab. 2009;9(5):397-408. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4757500/
Zhang et al. (2024) Resistant starch intake facilitates weight loss in humans by reshaping the gut microbiota. Nature Metabolism, pp.1-20. https://www.nature.com/articles/s42255-024-00988-y
Shen J, et al. Gut microbiota regulates bone density by modulating the RANKL-OPG system. Nature. 2019;569(7757):485-490. https://www.nature.com/articles/nm.4185
Li W, et al. Gut microbiota modulation as an emerging strategy for obesity control: mechanisms and potential applications. Food Sci Nutr. 2017;5(6):1209-1222. https://www.mdpi.com/2311-5637/8/8/376
Venkatraman A, et al. Effects of resistant starch on appetite, satiety, and postprandial glycemic control in healthy adults. Nutr J. 2015;14:67. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6316739/
Backhed F, et al. Turning clocks back: dietary modulation of ageing and metabolic disorder. Cell. 2007;130(5):741-750. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7995490/
Zhao L, et al. The role of gut microbiota in obesity and related metabolic disorders. Gut Microbes. 2018;9(4):252-271. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8903526/
David LA, et al. Metagenomic insights into the gut microbiome of overweight and obese humans. Cell Metab. 2014;20(3):611-622. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9373125/
Karlsson FH, et al. Gut metagenome in human obesity: a meta-analysis of 218 shotgun metagenomes. Nat Biotechnol. 2019;37(11):1211-1222. https://pubmed.ncbi.nlm.nih.gov/35467389/
Liu Z, et al. Fermentable fiber intake, gut microbiota, and metabolic health. Annu Rev Food Sci Technol. 2023;14:493-524. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7146107/
Björck I, et al. Resistant starch formation in waxy potato products: influence of added fat, salt, and storage. J Cereal Sci. 1990;12(2):129-138.
Sajilata MG, et al. Resistant starch content of green bananas at various stages of ripeness. J Food Sci Technol. 2006;43(2):160-163.
