The Macro Diet

Athletes and bodybuilders have been encouraging some form of the Macro Diet for decades. This eating style focuses on the macronutrient profile of foods, rather than calorie content. Most followers of the diet aim for higher protein, lower carb meals to help them reach their ideal weight and body composition goals.

Think of it this way: from a traditional calorie-counting perspective, a serving of cookies is equivalent to a serving of turkey – they are both about 150-170 calories. But from a macronutrient perspective, cookies are basically pure sugar and saturated fat, which can lead to more fat accumulation. Turkey, on the other hand, is mostly protein, which contributes to muscle formation, immune cell production and structural support.

The Macro Diet is designed to help people make healthier food choices. However, it can also encourage cutting out healthy carbs like fruits and whole grains so that dieters can ‘hit their macros’. Others may opt for calorie-free sweeteners and artificial fat-free ingredients to avoid going over their carb or fat limits. While these food choices may contribute to a leaner body composition, they aren’t exactly gut-friendly. For example, consuming non-caloric sweeteners, such as aspartame, saccharin and acesulfame-K, is linked to gut dysbiosis, glucose intolerance, and metabolic dysfunction.1 Furthermore, saccharin raises inflammation in the body, which can stimulate fat cell growth.2 Luckily, many of the unfavorable gut-related effects of the Macro Diet can be mediated through proper supplementation.


Probiotics can reverse the negative side effects of certain eating styles, while also helping dieters achieve their body composition goals. For example, Bacillus spore-based probiotics can reduce gut dysbiosis, improve gut barrier function and decrease metabolic endotoxemia. A recent clinical trial found that 30-day supplementation with Bacillus spore-based probiotics (MegaSporeBioticTM) significantly reduced biomarkers of leaky gut following a high fat meal by 60%.3 This was accompanied by a 24% reduction in serum triglycerides, and significantly lower levels of the inflammatory molecule known as IL-1β. Plus, Bacillus probiotics such as B. coagulans can actually help the body increase absorption of protein, leading to increased muscle gains. A recent study found that co-athletes consuming a combination of protein powder and B. coagulans showed improvement in muscle recovery and reduced muscle damage.4 Researchers speculate that this may lead to enhanced adaptation to training, improved muscle growth and enhanced performance. B coagulans is also a lactic acid producer, so it can keep the gut at a healthy pH.5


As healthy gut microbes gobble up prebiotic fibers and polyphenols, they produce short-chain fatty acid (SCFA) as a metabolic byproduct. These molecules fuel our gut cells and help maintain thriving gut health. Plus, SCFAs have anti-inflammatory and anti-cancer affects. Prebiotic fibers and polyphenols come exclusively from carbohydrate containing foods, such as fruits, vegetables and whole grains. Cutting out real foods and replacing them with artificial ingredients in order to hit your macros can affect short-chain fatty acid production. Low SCFA production is linked to numerous metabolic diseases, such as diabetes and obesity.

Fortunately, prebiotic compounds can be extracted from plants and taken as dietary supplements without contributing to carbohydrate intake. For example, xylooligosaccharides (XOS) is a prebiotic fiber that comes from honey, milk and a variety of fruits. This prebiotic fiber is shown to enhance populations of species such as Bifidobacterium and Faecalibacterium, which are both major producers of SCFAs.7, 8 Using XOS supplements can therefore greatly enhance SCFA concentrations in the gut! Plus, clinical trials show that XOS helps balance gut dysbiosis, and supports healthy blood sugar and triglycerides levels.9, 10

Apple and citrus polyphenols also act like prebiotics in the gut, helping to boost SCFA production. For example, a recent clinical trial found that citrus polyphenol supplements significantly enhance a group of species known as Clostridium cluster XIVa.11 These bacteria produce a substantial portion of butyrate in the gut microbiome. Butyrate is one of the most potent SCFAs and inhibits gut inflammation. Apple polyphenol supplements also greatly enhance gut health, leading to improved metabolism and reduced body fat.12


  1. Suez, et al. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014; 514(181–186).
  2. Bian, et al. Saccharin induced liver inflammation in mice by altering the gut microbiota and its metabolic functions. Food and Chemical Toxicology. 2017; 107: 530-539.
  3. McFarlin BK, et al. Oral spore-based probiotic supplementation was associated with reduced incidence of post-prandial dietary endotoxin, triglycerides, and disease risk biomarkers. World J Gastrointest Pathophysiol. 2017; 8(3):117–126.
  4. Jäger R, et al. Probiotic Bacillus coagulans GBI-30, 6086 Improves Protein Absorption and Utilization. Probiotics Antimicrob Proteins. 2018;10(4):611-615.
  5. Elshaghabee FMF, et al. Bacillus as Potential Probiotics: Status, Concerns, and Future Perspectives. Front Microbiol. 2017; 8:1490.
  6. Ríos-Covián, et al. Intestinal Short Chain Fatty Acids and their Link with Diet and Human Health. Front Microbiol. 2016;7:185.
  7. Finegold, et al. Xylooligosaccharide increases bifidobacteria but not lactobacilli in human gut microbiota. Food Funct. 2014 Mar;5(3):436-45.
  8. Na, Kim, et al. Effects of xylooligosaccharide intake on fecal bifdobacteria, lactic acid and lipid metabolism in Korean young women, Korean J. Nutr., 2007, 40, 154–161.
  9. Yang, et al. Xylooligosaccharides Supplementation Alters Gut Bacteria in Both Healthy and Prediabetic Adults: A Pilot Study. Front. Physiol. 2015; 6:216.
  10. Wayne, et al. Effects of Xylooligosaccharides in Type 2 Diabetes Mellitus. J Nutr Sci Vitaminol. 2008; 54:396-401.
  11. Salden, et al. Maastricht University; Maastricht, The Netherlands: 2019. Unpublished work
  12. Nagasako-Akazome, et al. Apple polyphenols influence cholesterol metabolism in healthy subjects with relatively high body mass index. J Oleo Sci. 2007; 56(8):417-28.

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