Table 2.

Experimental evidence of the effect of antibiotics or disrupted microbiota on host weight

Strain or species	Treatment	Dose	Timing	Diet	Effect on weight	Effect on microbiota	Reference
C57BL6J mice	Germ-free	NA	Lifelong	Western	Less weight gain than similarly fed conventionalized mice	Absent	Backhed68
CH3 mice	Germ-free	NA	Lifelong	Chow	No change	Absent	Fleissner70
				HFD	Greater weight gain
				Western	Less fat gain
Germ-free chickens	Penicillin	45.5 mg/kg diet	From birth	Chow	No effect on weight in germ-free chicks	Absent	Coates47
Chickens					Weight gain	Not done
NCS mice	Penicillin or terramycin	0.3 g/L water	Starting at 30-33 days of age for 1 week	15% gluten*	Weight loss	Terramycin: loss of Lactobacilli and Gram negative bacilli, increase in enterococci Penicillin 0.1 g: reduced Lactobacilli Penicillin 1 g: loss of lactobacilli and enterococci	Dubos51, 88
	Terramycin,	0.3 g/L		Pellets‡	Weight gain
	Penicillin or terramycin	0.3 g/L		15% casein§	Weight loss
	Penicillin	1 g/L			Weight loss
	Penicillin	0.1 g/L			No change
Ha/ICR mice	Penicillin or terramycin	0.3 g/L		Pellets‡	Weight gain
				15% casein§	Weight gain
ob/ob mice	Norofloxacin Ampicillin	1 g/L drinking water	17 days	Chow	Reduction in fat mass	Near elimination of aerobic bacteria, 3 log reduction in anaerobic bacteria	Membrez65
C57BL6 mice	Ampicillin & neomycin	1 g/L 0.5 g/L	4 weeks	HFD	Lower weight	lower Bifidobacterium, higher Lactobacillus, and Bacteroides/Prevotella	Cani52
ob/ob mice			4 weeks	Chow	Lower fat mass	lower Bifidobacterium, Lactobacillus, and Bacteroides/Prevotella
Ob-CD14KO	none	NA	Lifelong	Chow	Lower fat mass	Not done
Swiss mice	Ampicillin, neomycin, metronidazole	1 g/L	8 weeks	HFD	Less weight gain	Massive depletion of Bacteroidetes and Firmicutes, muli-log fold reduction in anaerobic and aerobic bacterial counts	Carvalho64
C57BL6 mice	Penicillin Vancomycin Chlortetracycline Pen. + Vanc.	1 mg/ kg body weight	3 weeks through life	Chow	Increased fat mass in all antibiotic groups	Increase in lachnospiraceae	Cho49
C57BL6 mice	Penicillin	1 mg/ kg body weight (0.007g/L drinking water)	Birth or 4 weeks, then lasting through life	Chow	greater increase in weight administered at birth, greater effect in males	No reduction in total microbial populations Consistently reduced Lactobacillus, Allobaculum, Rkenellaceae, and Candidatus arthromitus (SFB)	Cox50
C57BL6 mice	Penicillin		Lifelong	HFD at 17 weeks	Pen promoted the diet- induced obesity and related metabolic effects
C57BL6 mice	Penicillin		First 4 weeks, First 8 weeks, or lifelong	HFD at 6 weeks	Increased total, lean, and fat mass in all groups, greater effect in females
GF-swiss webster rats	Pen-microbiota	NA	3 weeks of age	HFD	Increased fat and total mass in recipients of microbiota from antibiotic-treated mice	Lower Lactobacillus, Allobaculum, and Rkenellaceae
C57BL6 mice	Vancomycin	2 mg/day	At weeks 12–20	HFD	Weight loss	Reduced Clostridium and Bacteroides, rise in enterobacteriaceae	Murphy66
Rats	Amoxicillin	150 mg/ kg body weight	At 5–15 days old	Chow	No change in weight	Reduction in Bacteroides, Lactobacillus, and Clostridium leptum cluster at day 21 of life	Morel67

^*gluten as a sole protein source (deficient in lysine and threonine)

^‡complex mouse diet from Dietrich and Gambrill, Frederick, MD,

^§casein as a sole protein source.

Abbreviations: HFD, high fat diet (45% calories from fat)