- Aug 15, 2018
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High-protein diets get planned to the gram. Fibre usually gets whatever is left over, which for a lot of lifters eating for size or leanness ends up being not much — and the research on gut health suggests that's a gap worth closing, even if it never shows up directly in a training log.
The basic physiology: gut microbes ferment fermentable fibre into short-chain fatty acids like butyrate, which feed the gut lining, support immune function, and appear to play a role in insulin sensitivity and inflammation regulation. Large cohort work, including a 2019 Lancet series of meta-analyses by Reynolds and colleagues covering 185 prospective studies, found that intakes around 25–29 g of fibre per day were associated with meaningfully lower rates of cardiovascular disease, type 2 diabetes, and colorectal cancer, with dose-response benefits extending higher. Most North American adults average closer to 15 g. Lifters eating lots of meat, dairy, and refined "bulking" foods can easily land below that.
For lifters specifically, the most directly relevant concern may be more mundane: digestive comfort and consistency. Very high protein intakes with low fibre are a recipe for GI misery that quietly caps how much food you can actually eat and absorb comfortably. There's also emerging (and still early) research on the gut-muscle axis — differences in microbiome composition between athletes and sedentary people, and small trials of specific probiotic strains on recovery and illness rates in athletes. A 2019 position stand from the International Society of Sports Nutrition on probiotics rated most claims as preliminary, with the most defensible finding being fewer or shorter upper-respiratory illnesses in some athlete trials. Anyone selling a probiotic as an anabolic is ahead of the evidence.
The boring play wins again: hit fibre gradually (a sudden jump causes its own GI problems), draw it from varied whole foods — oats, legumes, fruit, vegetables, whole grains — rather than a single supplement scoop, and keep fluids up alongside it. If a high-protein phase has your digestion in rough shape, fibre is the first dial most people should check before exotic gut protocols.
How much attention do you pay to fibre when the protein target is the priority, and have you ever had a phase where fixing digestion noticeably changed how well you could eat and train?
The basic physiology: gut microbes ferment fermentable fibre into short-chain fatty acids like butyrate, which feed the gut lining, support immune function, and appear to play a role in insulin sensitivity and inflammation regulation. Large cohort work, including a 2019 Lancet series of meta-analyses by Reynolds and colleagues covering 185 prospective studies, found that intakes around 25–29 g of fibre per day were associated with meaningfully lower rates of cardiovascular disease, type 2 diabetes, and colorectal cancer, with dose-response benefits extending higher. Most North American adults average closer to 15 g. Lifters eating lots of meat, dairy, and refined "bulking" foods can easily land below that.
For lifters specifically, the most directly relevant concern may be more mundane: digestive comfort and consistency. Very high protein intakes with low fibre are a recipe for GI misery that quietly caps how much food you can actually eat and absorb comfortably. There's also emerging (and still early) research on the gut-muscle axis — differences in microbiome composition between athletes and sedentary people, and small trials of specific probiotic strains on recovery and illness rates in athletes. A 2019 position stand from the International Society of Sports Nutrition on probiotics rated most claims as preliminary, with the most defensible finding being fewer or shorter upper-respiratory illnesses in some athlete trials. Anyone selling a probiotic as an anabolic is ahead of the evidence.
The boring play wins again: hit fibre gradually (a sudden jump causes its own GI problems), draw it from varied whole foods — oats, legumes, fruit, vegetables, whole grains — rather than a single supplement scoop, and keep fluids up alongside it. If a high-protein phase has your digestion in rough shape, fibre is the first dial most people should check before exotic gut protocols.
How much attention do you pay to fibre when the protein target is the priority, and have you ever had a phase where fixing digestion noticeably changed how well you could eat and train?