Hot off the presses this week, Critical Reviews in Food Science and Nutrition. Tim writes in email.
Hey, Guys, check this out. A new paper (review of other studies) just out this week. Kind of disappointing, but still a total 'Win' for us. The goal of the paper was to see if RS was a 'superfood' for losing weight. The answer is a resounding 'NO,' simply adding RS to one's diet does not lead to weight loss. It does however, lead to improved insulin sensitivity, reduced visceral fat, a reduction in inflammation, and reduced risk for diabetes, CVD, and cancer.
They seemed to have pinned down why it doesn't work for weight loss. And this should make everyone think about how silly the term 'weight loss' really is. RS is not a good weight loss tool because it leads to an increase in lean body mass!
So, I'm really glad that we never portrayed this as a weight loss tool. We are vindicated in our explanations of why RS is a good thing—and it ties intimately with the gut microbiome. Here are a few clips from the paper, but please have a read and see what you think. It basically describes every human and animal study ever done, but focuses mostly on weight loss and Total Energy Expenditure ('TEE').
"The obesity epidemic has prompted researchers to find effective weight-loss and maintenance tools. Weight loss and subsequent maintenance are reliant on energy balance-the net difference between energy intake and energy expenditure. Negative energy balance, lower intake than expenditure, results in weight loss whereas positive energy balance, greater intake than expenditure, results in weight gain. Resistant starch has many attributes, which could promote weight loss and/or maintenance including reduced postprandial insulinemia, increased release of gut satiety peptides, increased fat oxidation, lower fat storage in adipocytes, and preservation of lean body mass. Retention of lean body mass during weight loss or maintenance would prevent the decrease in basal metabolic rate and, therefore, the decrease in total energy expenditure, that occurs with weight loss. In addition, the fiber-like properties of resistant starch may increase the thermic effect of food, thereby increasing total energy expenditure. Due to its ability to increase fat oxidation and reduce fat storage in adipocytes, resistant starch has recently been promoted in the popular press as a "weight loss wonder food". This review focuses on data describing the effects of resistant starch on body weight, energy intake, energy expenditure, and body composition to determine if there is sufficient evidence to warrant these claims."
As Tim said, we have never once touted this as a weight loss deal. What we have been open to is the possibility that perhaps over as long a time as it caused to mess up a gut and gain a lot of fat, that with a clean diet incorporating RS, perhaps satiety signals will be better and a person might lose excess fat slowly. Since I began incoprating RS in April, I've dropped 10 pounds—about a pound per month—with doing absolutely nothing to try to lose weight. I only learned this just yesterday, because I hadn't stepped on a scale in quite a long time but noticed my face looked leaner. Was just going by how my pants fit, and I was satisfied. I also "feel" as though I've gained lean mass in upper body and thighs and anymore, I don't do much but walk and take hikes now & then. A little fun with the kettle bells in the backyard, now & then.
We got hold of the full text and here's some of the meat quotes with emphasis added.
"Despite numerous observations in rodents and humans describing no change in body weight, energy intake, or TEE in response to RS ingestion, almost every rodent study that has measured body composition finds lower fat mass (FM) and/or higher LBM with RS ingestion.
"These data have been scrutinized and replicated many times in different experimental paradigms, lending credence to the idea that RS causes changes in metabolic flux that act to increase fat oxidation with a concomitant decrease in carbohydrate and protein oxidation. Thus, RS could increase protein accretion (LBM) and reduce the amount of fat available for net storage without changing TEE. In addition, it has been shown that high fiber diets, such as a RS diet, cause lower total metabolizable energy than predicted/measured in vitro due to decreased in vivo digestibility of non-starch polysaccharides, carbohydrate, and fat (Behall and Howe, 1995). Thus, there may be less net carbohydrate and fat available for storage in response to a RS diet. [...]
"Taken together, these data provide convincing evidence that the gut microbiome can play a crucial role in the absorption and use of dietary nutrients as well as exhorting a strong influence the development of obesity. As RS can change the microbiome of the gut, it is reasonable to assume that RS consumption could influence the development of obesity and the success of weightloss/ maintenance attempts.
"Five important caveats regarding data interpretation were discussed:
1) Energy intake may be dependent on the energy density of the diet; future studies should consider this during the experimental design process.
2) Higher total bowel content, lumen thickness, and mass of the microbiome in response to RS ingestion can cause overestimation of total body weight.
3) Data in humans is from healthy adults who are able to effectively regulate body weight. It is likely that different effects would be observed in obese subjects.
4) Acute human studies have been too short to observe any effect of RS fermentation on TEE.
5) Visual analog scale estimation of hunger may not correlate well with food intake; therefore, data from subjective measurements should be interpreted carefully.
"It is apparent that ingestion of RS, relative to DS (digestible starch), has no effect on body weight in healthy rodents, no effect on energy intake, although this seems to be dependent on the energy density of the diet, and the effects on TEE are equivocal and require further investigation. However, there is strong evidence that RS lowers whole-body and visceral adiposity. The magnitude of these changes in adiposity are very large and sufficient to independently improve insulin sensitivity, and reduce the risk of diabetes, CVD, and certain cancers.
"Human data corresponds well with that from rats. RS, in comparison with DS, does not seem to have any impact on body weight, although studies in humans would need to be of longer duration in order to observe any such effect, has no effect on energy intake or TEE, and increases fat oxidation. There is a scarcity of data regarding the effect of RS on fat mass and LBM in humans. There is data from mice and humans to show that RS changes the microbiota in the gut which has been shown to influence energy absorption and the development of obesity.
"There is some scant evidence that the metabolic changes that occur in response to RS ingestion may not occur in obese rodents. Clearly, further studies need to be conducted in obese humans and rodent models before any conclusions can be drawn regarding the usefulness of RS in this population. A plethora of metabolic adaptations occur in obesity and in the weight-reduced state, including changes to the microbiota that influence energy absorption from the diet and obesity, and it is vital to determine if RS has any biologically relevant effects under these conditions. The observation that RS increases protein retention during overfeeding indicates that RS could have positive effects on body composition and, therefore, on BMR. Clearly, there is evidence that RS has effects, such as increased fat oxidation and reduced fat storage in adipocytes, that imply that it would be a useful weight-loss and/or maintenance tool. However, there is no direct data showing that RS has any impact on body weight, energy intake, or energy expenditure. Therefore, it is necessary to conduct well-designed studies, of sufficient duration, in obese individuals during periods of underfeeding, overfeeding, and energy balance before any meaningful conclusions can be drawn."
So there you have it. Pretty much as we suspected. Feed the gut, healthy gut. Healthy gut, healthier human. Healthier human, well regulated hormones and over time, nature takes its course in the most perfect way possible: Body Recomposition vs. simplistic "weight loss" strategies.
Anyone still think they don't have a "starch deficiency?"