No one diet is right for everyone. Our bodies, lives, and needs are all incredibly different. As they say, "One man's meat is another man's poison." It can take time to figure out which specific diet is best for you (food journaling, elimination diets, trial-and-error... or you could hire me to help!), but luckily, there are basic principles that work for everyone.
Brain fog, fatigue, bad breath, itchy skin, white tongues, frequent yeast infections, sugar cravings, and many other symptoms can be attributed to an overgrowth of a fungus that lives in your gut called Candida albicans. It's supposed to be there, but diets high in sugar, alcohol, and processed carbs, or a strong course of antibiotics, can be enough to upset your microbiome balance and lead to Candida overgrowth.