Hi Sara. It’s meant to be a guide, as each person’s (calorie) needs varies depending on age, gender activity level etc. However, the link to the Greek Nutrition Guidelines that I have also included at the end of the post provides serving sizes. Adding the link here too: https://www.olivetomato.com/eat-like-greek-greek-dietary-guidelines-a-better-choice/
Some of the concerns are around micronutrients — supplementation of electrolytes, vitamins, and fiber is often required on low-carb diets, Zeratsky says. And sometimes, these diets can actually lower the blood sugar of a person with diabetes to the point where it’s too low, which is also dangerous. (Low-carb diets are not recommended for those people with type 1 diabetes or anyone on insulin due to that risk, experts note.)
On a ketogenic diet, your entire body switches its fuel supply to run mostly on fat, burning fat 24-7. When insulin levels become very low, fat burning can increase dramatically. It becomes easier to access your fat stores to burn them off. This is great if you’re trying to lose weight, but there are also other less obvious benefits, such as less hunger and a steady supply of energy. This may help keep you alert and focused.