Although the compositional alterations of gut bacteria in ketogenic diet (KD) have been intensively investigated, the causal relationship between this extreme diet and the microbiota changes is not fully understood. Here, we studied the growth dynamics of intestinal bacteria in KD. We used the CoPTR method to calculate the peak-to-trough ratio (PTR) based on metagenomic sequencing data, serving as an indicator of bacterial growth rates. Notably, Akkermansia muciniphila, a bacterium strongly linked to the therapeutic benefits of KD, exhibited one of the highest growth rates, aligning with its markedly elevated abundance. Our findings also revealed discrepancies in the change patterns of CoPTR values and relative abundances for various bacteria across different diet groups, some of which might be attributed to the exceptionally high or low growth rates of specific species. For some of the species demonstrating obvious differences in growth rates between KD and standard diet, we conducted in vitro culture experiments, supplementing them with diverse nutritional sources to elucidate the underlying mechanisms. The integrative analysis of bacterial abundance and growth dynamics can help deepen our understanding of the gut microbiota changes caused by KD and the therapeutic effects of this special diet.