A Dietitian’s Guide to the Gut Microbiome, Genetics, and Weight Loss

Beyond Counting Calories: Unveiling the Science of Nutrition and Weight Management. Explore the intricate relationship between gut health, genetics, and food choices in the battle against obesity.

We’ve all heard or said the words ourselves: “I can’t eat that, it has too many calories”, as many of us have taken on the monumental task of counting calories. There are a plethora of apps that allow you to track the food you eat, count calories, and pull in data on calories burned from physical activity.

So, with so many of us counting and tracking our calories taken in and trying to balance it with calories we expend, why is more than 70 percent of the adult population in the United States overweight or obese?

Let’s explore. 

The Problem with Counting Calories

Clearly, not all calories are created equal. Let’s compare a 100-calorie serving of gummy bears to a 100-calorie serving of broccoli. 

A 100-calorie serving of gummy bears, approximately 18 pieces will have a gram or two of protein and a whopping 22-25 grams of added sugar. In comparison, a 100-calorie serving of broccoli, approximately 3 cups, boasts 6 grams of dietary fiber, 0 grams of added sugar, greater than 100% of the daily value for vitamins C and K and nearly 50% of our daily need of folate. It will also provide us with some potassium, magnesium, iron and calcium. In addition, it is rich in other plant compounds such as sulforaphane and carotenoids which protect our body from oxidative damage and support our natural detoxification systems. 

Understanding Your Gut Microbiome

Ninety percent of gut bacteria are in 1 of 2 families: Bacteroidetes and Firmicutes. Firmicutes generate more harvestable energy than Bacteroidetes. Firmicutes thrive on added sugar, such as the sugar found in the gummy bears. Obese humans have relatively more Firmicutes, as do rodents placed on a high sugar and high fat processed western diet. 

High ratios of Firmicutes to Bacteroidetes also alters the production of short-chain fatty acids needed to maintain the health and integrity of the gastrointestinal tract. Low levels of these short-chain fatty acids promote low-level inflammation. When this happens, toxins that should remain in the gut end up flowing into the blood, contributing to insulin resistance (which can contribute to unwanted weight gain) and Increased production of ghrelin (the appetite stimulating hormone). 

Kat Benson, CSSD, CPT at VNutrition adds: Because of the insulin resistance, our body needs to send more insulin into the bloodstream to regulate our blood sugar. High levels of circulating insulin promote more belly fat and also blocks leptin, our satiety hormone from working in the brain. So now, we have more of the appetite stimulating hormone, our satiety hormone isn’t working like it should, AND our body chemistry is set up to store belly fat. 

In contrast, fiber, like that found in broccoli, helps to fuel the Bacteroidetes. So, the “Lean Phenotype” – has a higher ratio of Bacteroidetes to Firmicutes. It also helps your body produce more short-chain fatty acids which are the preferred fuel source for healthy cells lining the intestinal tract. There is reduced inflammation and less chance of insulin-resistance, reducing our risk of storing belly fat and keeping our hunger and satiety hormones in balance. 

What is Nutrigenomics?

There is a science-based tool available to create personalized nutrition recommendations known as nutrigenomics or nutritional genomics. With this testing, we can assess how our genetic information influences how our body responds to food and how things like our weight and nutritional status are impacted. 

Our genes dictate how certain proteins like enzymes and hormones respond to the food we consume. Certain variations of genes can determine how many enzymes, hormones and other functional proteins our body will make as well as how efficiently these proteins will work. 

Research continues to grow in the field of nutrigenomics that demonstrates how variations within our genes can impact how our body will handle the nutrients we consume. One-size does not fit all. Likewise, whether or not a gene is “turned-on” or “turned-off” can depend on the food we eat. 

The Impact of Genetics on Metabolism and Calorie Balance

Let’s look at a couple examples of how this relates to calories. 

One of my clients, we will call him Tom, completed nutrigenomic testing. His results showed that he has a specific variant of a gene known as the fat mass and obesity gene or the FTO gene. This gene plays a role in your metabolism, calorie expenditure and calorie balance. Because of the variant he possesses, he has an elevated weight reduction ability when he eats a moderate to high protein diet. 

Tom’s wife, we will call her Gladys, possessed a variant of the TCF7L2 gene. Because of this variant, eating a higher fat diet significantly increases the risk of being overweight or obese as well as being insulin resistant. So, for weight loss purposes, we found that it was better for Tom to have more of his calories come from higher protein foods, while it was better for Gladys to have more of her calories come from lower fat foods. Again, one-size does not fit all. 

How to Optimize Your Microbiome for Weight Loss

Rachel Gargano, MS, RD, CSSD, CBS at Live it Up, recommends incorporating green powders that provide a complete source of fiber and probiotics, to help complement overall nutrition and address potential deficiencies.

Not only does a high fiber diet support a gut microbiome that promotes leanness, it also has the capacity to turn on diabetes and obesity fighting genes. Choosing quality calories appears to matter far more than quantity of calories in the battle of the bulge.

  •  Eat mostly whole, unprocessed foods such as non-starchy vegetables, bright colored starchy veggies like sweet potatoes and squash, nuts, seeds and other healthy fat and grass-fed, pasture-raised organic protein rich foods. 
  • Keep added sugar to a minimum. The recommendation is for males to get no more than 36 grams of added sugar in a day. 
  • Finally, consider nutrigenomic testing to further understand how your body responds to the nutrients you consume. 
Scroll to Top