An interesting study published in the journal Obesity points out that eating more soluble fiber, like that from apples and beans, and moderate exercise will selectively decrease belly fat.1 The authors don’t seem to know why it is selective to belly fat, and not subcutaneous fat (fat just under the skin). I think one reason would be that the intake of high amounts of soluble fiber promotes growth of beneficial bacteria that produce short chain fatty acids, both of which may control some of the inflammation in the gut. Chronic inflammation causes marked increase in insulin resistance, and therefore, storage of more belly fat. Controlling this inflammation is key, and as we see, can be done by consuming soluble fiber.
Here are some recently discovered points that support the above concepts:
- Eating a high fat and sugar diet decreases the number of beneficial bifidobacteria and increases the number of potentially pathogenic gram negative bacterial species in the gut.
- As these potentially pathogenic bacteria die they release cell wall lipopolysaccharides (LPS) which happen to also be better absorbed through the gut lining when eating a high-fat, high-sugar, low-fiber diet on a regular basis. The LPS molecules easily pass through the epithelial gut lining and hit the gut immune system where they activate white blood cells including neutrophils, monocytes, and macrophages that all then release inflammatory cytokines: TNF alpha, IL-6 and IL-1 beta. These inflammatory cytokines can trigger inflammation in the small blood vessels throughout the body but probably start with the blood vessels in the intestines, causing endothelial dysfunction. This has been proven by measuring a significant decrease in blood vessel wall flexibility within minutes to hours after eating a high-fat, high-sugar meal.2
- Conversely, supplementing with bifidobacteria and eating a plant-based, high-fiber diet seems to decrease translocation of LPS through the gut epithelial lining and may help prevent the negative effects of high-fat diet induced metabolic diseases.3
- The vascular inflammation in and around the intestinal tract, which is 20 or more feet in length, can stimulate stem cells adjacent to the blood vessel walls (known as stem cell pericytes) to develop into fat cells or adipocytes which accumulate wherever there are blood vessels in the abdomen—that’s almost everywhere!
- The inflammatory fire continues as the abdominal fat, or visceral fat (some people call it VAT) continues to produce more inflammatory cytokines (IL- 6, TNF alpha, etc.) that flow into other blood vessels, stimulating more stem cell conversion into fat cells or adipocytes.
- It is interesting that both vitamin D and stem cells are stored at high levels in abdominal fat. Perhaps the vitamin D is trying to cool down the inflammation and the stem cells are there to respond according to the body’s information: either make fat or something else.
It makes sense that exercise was found helpful for reducing abdominal fat. Exercise has many benefits. For one, it produces more adiponectin to help reverse the situation. Adiponectin is an anti-inflammatory hormone made in fat that both decreases inflammation in fat and travels to the pancreas to help sensitize and balance the release of insulin which can help reverse metabolic imbalances.
So it is pretty simple—eat your plant-based, high-fiber diet, supplement with probiotics (including good amounts of bifidobacteria), and exercise moderately on a regular basis. Then be patient. The accumulation of abdominal fat, along with all the problems caused by this fat, including heart attacks and cancer, is reversible.
1. Hairston KG, et al., “Lifestyle Factors and 5-Year Abdominal Fat Accumulation in a Minority Cohort: The IRAS Family Study.” Obesity (Silver Spring). 2011 Jun 16. doi: 10.1038/oby.2011.171. [Epub ahead of print]
2. Plotnik GD, et al., “Effect of antioxidant vitamins on the transient impairment of endothelium-dependent brachial artery vasoactivity following a single high-fat meal.” JAMA. 1997 Nov 26;278(20):1682-6.
3. Cani PD, et al., “Selective increases of bifidobacteria in gut microflora improve high-fat-diet-induced diabetes in mice through a mechanism associated with endotoxaemia.”
Diabetologia. 2007 Nov;50(11):2374-83.