Many diet plans cut out entire food groups, which can create nutrient deficiencies as well as health problems. For instance, if the diet is very low in carbohydrates and you have type 1 diabetes or type 2 diabetes, it’s probably not a good fit. And if it’s too restrictive and you’re pregnant or breastfeeding, it’s not a good idea, either. Keep in mind that pregnancy is not a time for weight loss. Speak with your doctor before making any changes to your diet if you are pregnant or breast-feeding.
"Crash diets (dramatically cutting down how much you eat) might help you to lose a few pounds at first, but they’re hard to sustain and won’t help you keep the weight off. It might seem like a quick and easy option, but eating too few calories can actually do more harm than good. If your calorie intake dips too low, your body could go into starvation mode. This will slow down your metabolism, making it harder for your body to lose weight. Make sensible, healthy changes to your lifestyle that you can stick to and avoid the fad diets."