Peer-reviewed publication · Companion animals · In the living system
A high-protein, low-carbohydrate diet shifted faecal bacteria in overweight cats, while no single group changed in lean cats.
- No humic or fulvic material tested
At stable body weight, a high-protein, low-carbohydrate diet shifted faecal bacteria more clearly in overweight cats than in lean ones; it was not a weight-loss study, and microbial functions were predicted, not measured.
Li and Pan, 16 October 2020. Frontiers in Microbiology 11:591462.
Scope, material and route
- Studied
- Neutered domestic shorthair cats, mean age about 7 years; lean (body condition 4 to 5 of 9, body fat 20 percent or less) or overweight (7 to 9 of 9, body fat 25 percent or more)
- Design
- Eight weeks on the control diet for all cats, then eight weeks with cats in each body condition group randomly assigned, balanced for sex, age and body fat, to continue the control diet or switch
- Setting
- Individually housed colony cats with a shared activity room; protocol approved by the funder's animal care committee
- What changed
- Isocaloric dry diets with animal protein as the primary source; protein raised by replacing grains with plant protein
- Route
- Feed, fed to maintain body weight
- Exposure
- 51.35 percent protein and 11.60 percent carbohydrate against 32.43 and 32.30 percent; fat 14.60 against 14.30 percent; total dietary fibre 12.70 against 11.20 percent. Study exposure, not application guidance.
- Duration
- Eight weeks baseline, then eight weeks intervention
Study design
Lean cats
19 cats10 switched to high protein; 9 stayed on the control diet.
- Overall communityShifted with diet (P = 0.008)
- Individual taxaNone differed
Overweight cats
20 cats10 switched; 10 stayed on the control diet.
- Overall communityShifted with diet (P = 0.000029)
- Fusobacteria8.1-fold higher on high protein
- Five generaShifted in relative abundance
What kind of result
- MeasuredBacterial composition, by 16S sequencing; body fat
- Predicted, not measuredMicrobial pathways, inferred from 16S data
- Not measuredShort-chain fatty acids and other metabolites
Sixteen weeks, by week
One faecal sample per cat at the end of each phase, weeks 8 and 16, marked above the bar.
- Control diet, all cats 8 weeks
- Assigned diet 8 weeks
More study details
- Research question
- How does a high-protein, low-carbohydrate diet change the faecal microbiome of overweight compared with lean cats?
- Experimental unit and sample size
- The individual cat; 39 cats (lean: 10 high-protein, 9 control; overweight: 10 and 10); 77 faecal samples, one lean cat having no final sample
- Comparator
- Cats in the same body condition group that continued the control diet
- Outcomes measured
- Faecal bacteria by 16S rRNA gene sequencing (V3 to V4), body weight, body condition and body fat by quantitative magnetic resonance; microbial pathways predicted with PICRUSt
Findings
Researchers at Nestlé Purina fed 20 overweight and 19 lean adult cats a control diet (32.4 percent protein, 32.3 percent carbohydrate) for eight weeks, then randomly assigned about half of each group to a high-protein, low-carbohydrate diet (51.4 and 11.6 percent) for eight more weeks, feeding to maintain body weight. Faecal bacterial communities differed by diet in both groups, more strongly in overweight cats. In overweight cats Fusobacteria rose about eightfold and five genera described as short-chain fatty acid producers shifted; in lean cats no individual taxon differed. Body fat did not change. Fatty acids were not measured, functional pathways were predicted rather than measured, and both authors are employees of the funder.
| Outcome | Comparison or result | Interpretation |
|---|---|---|
| Body fat | No change from start to end in any group (P > 0.05) | Weight was held steady by design |
| Overall community (unweighted UniFrac) | Differed among the four body condition and diet groups (P = 0.000001); diet effect P = 0.000029 in overweight and P = 0.008 in lean cats | Diet changed the overall community in both groups |
| Individual taxa, lean cats | No taxon differed between diets at any rank (adjusted P > 0.05) | A null at the level of single taxa |
| Fusobacteria, overweight cats | 3.89 against 0.48 percent, 8.1-fold higher on the high-protein diet (adjusted P = 0.001) | A large relative increase |
| Genera, overweight cats | Faecalibacterium (4.5-fold) and Fusobacterium higher; Megasphaera, Veillonella and Bifidobacterium lower on the high-protein diet (adjusted P < 0.05) | Shifts in relative abundance; the fatty acids these genera produce were not measured |
| Clostridium, overweight cats | Higher on the control diet before adjustment (P = 0.007), not after (adjusted P = 0.057) | Not statistically supported |
| Alpha diversity | No difference between lean and overweight cats after baseline; at the end, Faith's PD 27.0 (lean, high-protein) against 30.5 (overweight, control), P = 0.019 | A difference between groups, not a clear diet effect |
| Microbes and clinical measures | No association between microbial abundance and age, sex, body weight, body condition or body fat | No link to body measures in this study |
| Predicted pathways | Pathways for energy and one-carbon (folate) metabolism enriched in overweight control cats; none in lean cats | Predicted from 16S data, not measured |
High-protein diet against control diet at the end of the intervention unless stated. Fold changes and adjusted P-values are from Table 3. Values are extracted from the source as reported; no raw data were available.
Interpretation and limits
What this record supports
A shift in the relative abundance of several faecal bacterial groups in overweight cats fed this high-protein, low-carbohydrate diet for eight weeks at stable body weight.
What remains uncertain
- Function. Short-chain fatty acids and other metabolites were not measured; calling the genera fatty acid producers draws on other studies, and the pathways were predicted from 16S data.
- Health. No weight loss, metabolic or clinical outcome was assessed, and cats were fed to keep weight stable, so the result does not show a weight-management effect.
- Lean against overweight. The stronger response in overweight cats rests on comparing results within each group; no diet by body condition interaction test is reported, and lean cats did show an overall community shift (P = 0.008).
- Statistics. Taxon tests compared end-of-baseline samples as a third group alongside the two end-of-intervention groups, though they came from the same cats.
- Reporting. The pathway count (nine) does not match the pathways listed; the Fusobacteria adjusted P-value is 0.001 in Table 3 and 0.01 in the discussion; the pathway threshold is P < 0.01 in the results and P < 0.05 in the supplementary table title.
- Transfer. Colony cats on two experimental diets in which plant protein replaced grain; commercial diets differ in more than one nutrient at a time.
Which part of the framework it informs
Environmental conditions
The physical, chemical and management context.
Microbial activity
What microbial communities do within that context.
This record informs this area.Observable function
What can be observed or measured in the host or wider system.
This record informs this area.
- a Colon wall
- b Food residue
- c Bacteria
- d Mucus layer
Source, funding and review
- Source type
- Peer-reviewed publication
- Associated products
- No humic or fulvic material was tested. This record does not assess an associated product.
- Funding and relationships
- Funded by the Nestlé Purina PetCare Company. Both authors are employees of the company; one designed the diets, and the protocol was approved by the company's own animal care committee. The funding statement says the funder was not involved in the study design, data collection, analysis, interpretation or writing.
- Review status
- Prepared as an editorial summary. External scientific review has not been completed.
- What was read
- Full text read on PubMed Central (full-text XML via Europe PMC). Supplementary tables and figures were not read.
- Original title
- Differential Responses to Dietary Protein and Carbohydrate Ratio on Gut Microbiome in Obese vs. Lean Cats
- Authors
- Li Q, Pan Y
- Publication
- Frontiers in Microbiology 11:591462, 16 October 2020
- DOI
- 10.3389/fmicb.2020.591462
- Summary prepared by
- Carbon Biome Project
- Date added
- 19 October 2026
- Cite this summary
- Carbon Biome Project. A high-protein, low-carbohydrate diet shifted faecal bacteria in overweight cats, while no single group changed in lean cats. Evidence library record, added 19 October 2026. carbonbiomeproject.com/evidence/li-pan-2020-protein-carbohydrate-obese-lean-cats/