Fitness trends that negatively impact fat-loss goals by disrupting the gut and metabolism

The standard playbook for upping one’s fitness and fat-loss game generally includes:

  1. Eating more protein, often in the form of protein shakes and smoothies
  2. Changing our calorie intake by following a certain diet, these days its generally Whole 30, Paleo, Keto or Intermittent Fasting...
  3. Increasing frequency of exercise
  4. Cutting back on alcohol, sugar and other treats

Most of these actions can be really helpful at getting us results BUT many popular versions of these changes, negatively impact the metabolism by changing the landscape of the gut microbiome resulting in digestive distress, increased appetite and weight gain. 

With regards to leanness and decreased fat-stores, the peer-reviewed literature consistently demonstrates a difference in the microbial communities of individuals with more efficient metabolisms and leanness than those struggling with increased fat-stores and metabolic disorders. (Here, here, here and here).

And so far we know that different forms of diet, stress, movement, and ingested chemicals select for different members of the microbial community. 

Therefore when it becomes IMPERATIVE that we take a second look at some of the strategies being employed by the diet and exercise community to be sure that folks are making positive changes that will ultimately achieve the goals they working so hard to meet!


Protein shakes

The evidence is clear, if you want to change your body then you have to eat lots of lean protein. Read more about the benefits of a high protein diet here.

The standard recommendation for protein consumption (with lean muscle synthesis and fat-loss being the primary goal) is .8g-1 grams or protein per lb body weight each day, sometimes more if you are SUPER active!

And since protein powder is SO dang convenient, it’s no wonder that we see folks consuming 1-2 shakes a day to meat their appetite and protein demands. 

I recently saw an online personal trainer saying, “Don’t waste money on the expensive stuff, it’s all the same.”

While there are many instances when it is NOT necessary to spend money on the MOST expensive product available, but this is not one of them. 

I blacked out the product name listed here, so as not to pick on any one manufacturer.

I blacked out the product name listed here, so as not to pick on any one manufacturer.

Protein powder is a processed food and therefore an amalgam of different food items and chemicals.

It’s often made in the cheapest way possible AND it’s also a very convenient place to hide byproducts from the agricultural industry. 

It can be full of nutrition, but it can also contain food additives, synthetic sweeteners, inferior forms of whey, even toxic chemicals like heavy metals, additives like "natural flavoring" and thickeners, all of which negatively impact the efficiency of the metabolism by disrupting the gut. 

In many cases the more expensive products are made from a better quality of organic whey, soy, pea or hemp and contain fewer toxic ingredients.

Sweeteners **
You will find these ingredients in LOTS of other foods besides protein powder!

Acesulfame potassium (Ace-K) and sucralose (Splenda) are two of the most popular synthetic sweeteners that we see in protein powders.

Both Ace-K and sucraolose are FDA-approved sweeteners, but much like Aspartame, research on these compounds done AFTER their FDA approval is showing that these compounds disrupt the microbiome of animals, which negatively impacts the fat-storing mechanisms of the metabolism and causes increased bodyweight. 

Photo credit: Science Magazine

Photo credit: Science Magazine

In 2017, Xiaoming Bian et al, 2017  found that Ace-K changes the bacterial landscape of the gut by increasing the population of endotoxin-producing bacteria. 
As a result they saw an increase in systemic inflammation and increased metabolic stress, BOTH of which we know cause increase cravings and fat storing. (Kresser, 2010) 

One of the biggest problem with chugging protein powders that contain artificial sweeteners is that sucralose and Ace-K have been shown to cause an increase in appetite AND a preference for sweeter foods. (Mattes and Popkin, 2008).

Um, not ideal when you're trying to cut back on sugary, starchy foods to balance your blood sugar and reduce fat stores!

I'd also like to mention that in in addition to negatively impacting the gut and sugar cravings, the methylene chloride found in Ace-K is carcinogenic and can cause headaches, depression, nausea, mental confusion, liver effects, kidney effects, visual disturbances, and cancer in humans.

I encourage my clients to use protein powders that are sweetened with Stevia (if they like it), coconut sugar, or use an unsweetened protein powder (there aren't many of these!) and add their own sweetness via honey, coconut sugar, or fruit. 


Whey is the most popular source of protein found in protein powders because it's just so darn good at growing lean muscle!

Unfortunately, lots of folks have dairy intolerances or difficulty metabolizing either whey or the trace amounts of lactose that comes with the whey. 
Continue ingestion of a food that is distressing your gut, will cause inflammation and erosion of the mucosal lining of your intestines, leaky gut syndrome, metabolic stress (which leads to increase cortisol and fat-storage) and definitely elimination struggles like diarrhea and or constipation

If you experience excessive gas, bloating, abdominal cramping, or elimination struggles, try a protein powder made from organic pea or hemp protein.

But even if you don't struggle with dairy intolerance and your gut is cool with whey-based protein powders, you're still going to want to be selective about your whey products. 

Choose whey produced from organic and or grass-fed cows.
Nutrition-wise, this is your best option because healthy cows produce nutrient dense milk, and we know that good nutrition is the MOST impactful variable when it comes to sustainable fat-loss.

Photo courtesy of the Wall Street Journal

Photo courtesy of the Wall Street Journal

This source of whey will help you to avoid chemicals like antibiotics, synthetic hormones, pesticides and herbicides will help prevent metabolic disregulation associated with the ingestion of these compounds. While drinking a protein shake here and there that contains these chemicals, might not be problematic, lots of people are consistently consuming 1-2 protein shake a day FOR YEARS!!

"Most commercial whey powders are high-heat-treated, acid-flushed, and stripped of vital nutrients, creating an imbalanced, acidic "whey isolate" that's frequently contaminated with synthetic additives, chemical detergents, and heavy metals. It's no wonder that many of these whey products are hard to digest and have to cover up their acidic aftertaste with unhealthy sweeteners and artificial flavors". (Food Matters)

 A 2012 Consumer Reports' test showed that 3 of the 15 protein drinks tested contained risky levels of arsenic, cadmium, and lead all of which have been shown to negatively impact the gut microbiome. (Foligne, et al.,2013)

And while I know it's super annoying to have to choose the more expensive option here, in addition to helping you synthesize lean muscle, feel satiated and avoid over-consuming calories, good quality grass-fed or organic whey protein concentrates provides a number of health benefits that you can read more about here.


Locust beans. Photo courtesy of Dupont.

Locust beans. Photo courtesy of Dupont.


In many protein powders, you will find thickening agents that are used to alter the texture and appearance of (often inferior) protein powder locust bean gum, guar gum or carrageenan. It's still unclear how harmful these chemicals are when ingested, but all three of these additives have been linked to gastrointestinal disturbances like intestinal permeability and diarrhea. Not Ka-Blamo

Again, this is a situation where consuming these food items from time to time, might not be problematic, but routine daily consumption does cause many a person digestive distress AND increased sensitivity to these ingredients.
And at the end of the day, they are not necessary, so it's to your advantage to pay a little more for a better product that doesn't include them. 


Natural flavoring


Many a food item, inclusion protein powders, have "natural flavoring" listed on their label. 

According to FDA, “The term natural flavor or natural flavoring means the essential oil, oleoresin, essence or extractive, protein hydrolysate, distillate, or any product of roasting, heating or enzymolysis, which contains the flavoring constituents derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or similar plant material, meat, seafood, poultry, eggs, dairy products, or fermentation products thereof, whose significant function in food is flavoring rather than nutritional.”

Because "natural flavoring" is approved by the FDA, manufacturers do not need to disclose the specific ingredients of the “natural flavors” added to the food product. 
This is particularly problematic for folks with food intolerances, sensitivities and allergies, because they can unwittingly ingest chemicals that irritate their digestive systems without even knowing it!

Bottom line?

Photo courtesy of

Photo courtesy of

Individuals on higher-protein diets burn more fat and build more lean muscle.
Protein makes us feel full fast and for long periods of time, which is extremely helpful when trying to manage caloric intake. 
The body has to burn calories in order to utilize protein as a source of fuel.
This again helps to lower caloric intake. 
Protein provides the body with essential amino acids for lean muscle synthesis. 

High protein diets also support a healthy comment of microbes which again, play an important role in metabolism and fat-loss. 

So by all means keep your protein intake up AND keep it simple. 
I am a HUGE supporter of convenience and ease when it comes to cultivating nutrition practices and I often recommend that my clients use protein powder to this end. 

BUT I can't stress enough the importance of choosing protein powders made from the best quality ingredients with minimal additives. 

It will make all the difference to the health of your gut, which will set you up for sustainability and ease in achieving and maintaining your fitness goals!


.....Next up. Trend #2. How your newest diet impacts your microbial community, metabolism and fat-loss/phsyique goals!



Sarah Smith is a trainer, lifestyle coach and postnatal fitness specialist that specializes in helping women feel strong, confident and capable in their bodies!
Her specialties include kettlebells, gut health and optimization for fitness goals, pelvic floor health and function and making fitness fun! Check her out on social media here or email her!