Weight is much more than stored excess calories. It can be a symptom that metabolism is out of balance. While the old truth of eat less, move more remains true, the metabolism of weight involves a complicated mixture of biochemical signals and pathways that significantly impact how much you eat and perhaps even how much you move.
Resistant starch helps with the metabolism of weight in at least four ways:
1. It lowers the insulin levels in the body by increasing insulin sensitivity and lowering the levels of insulin in the blood. Click here for additional data on insulin sensitivity.
One of the most critical hormones driving weight gain is insulin. When we are young and metabolically very healthy, our tissues respond very quickly to insulin. As we age and/or our bodies repeatedly respond to rapid and high levels of glucose, the insulin receptors in muscles and tissues can become less sensitive to insulin, and take longer to transport glucose into the muscles. When this happens, the glucose stays in the blood longer and, the pancreas produces more insulin until the glucose levels fall. With enough insulin, the blood sugar levels return to normal. The higher levels of insulin causes fat to be stored and prevents fat from being burned, so losing weight becomes harder and harder with higher insulin levels. As the sensitivity to insulin gets worse and worse, the weight gets harder and harder to control. Loss of insulin sensitivity is an underlying mechanism which drives both the development of type 2 diabetes as well as obesity.
We do not feel differently, but increased insulin marks the decline of metabolic health. It may be ten or fifteen years before we discover that we have been losing insulin sensitivity. If someone has a higher genetic risk, it could happen much faster.
2. Resistant starch reduced lipolysis and increased fat burning in adults. Two studies showed a decrease in non-esterified fatty acids (NEFA) released from fat tissue and a reduction of lipolysis (fat storage), Robertson AJCN 2005 and Bodinham EC 2014. Another study found that resistant starch increased fat burning when measured by Respiratory Quotient, HIggins NM 2004.
- Many animal studies suggest that resistant starch’s fermentation, which increases the production of GLP-1 and PYY may be the key mechanisms for this benefit, i.e., Zhou MNFR 2015.
3. Resistant starch increased satiety and reduced feeling of hunger:
- after 2 or 3 hours – Willis NR 2009, Anderson AJCN 2010, Giuntini FRI 2015, Sarda JFF 2016 and Ble-Castillo N 2017. This is likely due to slower digestion and release of glucose deeper into the small intestine – a slowly digestible starch component that is not resistant enough to reach the large intestine but is still somewhat resistant to digestion, or to satiety hormones generated from food consumed within the previous 24 hours.
- after 7 hours, 10 hours and up to 24 hours – Nilsson JN 2008 and Bodinham BJN 2010. This may be due to resistant starch’s fermentation and cascade of metabolism effects triggered from the large intestine. Al-Mana and Robertson N 2018 fed participants resistant starch for breakfast and lunch and reported significantly reduced food consumption at dinner, but the benefit was lost when the whole 24 hour intake was evaluated.
4. Resistant starch helps to reduce the caloric density of foods. It delivers between 2 and 3 kilocalories/gram vs. 4 kcals/g for the flour that it commonly replaces. While this is simple and easy to explain, the caloric content is probably the least important of all of resistant starch’s benefits.