1) Their macros are incorrect, and they are consuming either too little or too many carbohydrates.
Low-carb diets affect everyone differently, so you’ll have to figure out how many you need based on your genes and activity level.
2) They aren’t getting enough fat in their diet.
The body requires fat resources to generate hormones that are critical to metabolism and wellness.
3) They consume too many processed foods while consuming insufficient fruits and vegetables.
Remove any high-carb, processed-fat foods from your diet, such as bread, cereal, and sweets, and replace them with vegetables.