Be Slim Keto:-Butter, nuts, coconut and olive oils, and fatty cuts of meat are all on the menu. However, don't go overboard with polyunsaturated fats like soybean, corn, or sunflower oil. Keto dieters who increase their intake of those fats often end up with gastrointestinal distress that causes them to jump ship. "In the beginning, I was terribly worried that I would lose muscle mass because of the low protein intake," he says. "But, I lost absolutely no muscle and was able to add lean mass to my physique. How is this possible? It's because ketones have a 'protein sparing' effect. So tons of protein is not necessary."