Have heard and seen that antibiotics can cause weight gain. how can this be combated?

Try Probiotics: Antibiotics often kill all the friendly bacteria in the gut, which interferes with good digestion. Also can increase candida (yeast) in the gut which often causes weight gain. Take a probiotic that has billions several types of friendlies, and also a friendly yeast, like saccharomyces to inhibit candida. As for diet, go low carb.