My Dr put me on a "low fat / low cholesterol / low carb" diet last week.

I am fairly active - I play soccer twice a week and I am starting Insanity tomorrow.

Why low carb? I thought since I will be active, I would need more carbs. What is the point of reducing carbs? How does it help me?

I would call your physician's office and ask, since we don't know your medical information it is hard to guess why a particular diet was prescribed!

I would ask for more of an explanation. If you are going low carb, you need a decent amount of fat in order for you to lose weight. It sounds odd and against conventional diets but if you google low carb eating, you will see the reasoning behind it. You will not be able to sustain a lifestyle that is low fat and low carb. You will feel hungry all the time. There are lots of resources here for calorie counting and carb counting as well as other diet plans that you can look at and decide what's right for you.

Little FYI, doctors receive virtually NO nutritional training, seriously. If your doctor has dietary concerns for you beyond weight loss the first thing you need to understand is what they're specifically concerned about (A1C results, blood sugar, cholesterol, triglicerides, etc., IOW, get a copy of your blood tests) then get them to refer you to a good certified nutritionist.

I would personally be waayyy more concerned with the "low fat" part. It sounds to me like what he was trying to prescribe was a moderate diet - because all that leaves you with is high protein.

You need healthy fats way more than you need carbs. Low carb dieting provides a lot of benefits, but you need to have your macros, particularly FAT intake, right.

Get a referral, and do some research of your own on the macro combination you need for your specific lifestyle.

I would guess you may have aberrant glucose readings, high blood pressure and/or high cholesterol and high triglyceride levels. It would depend how much overweight you are, but your doctor may be concerned that you have metabolic syndrome or are pre-diabetic. Low carb can help you loose weight when you are or are becoming insulin resistant. Low fat I could see when you are significantly overweight.

There are books on the science behind low carb diets. One I have read is by Phinney and Volek. I think it is "low carbohydrate living" or something. They research the Atkins diet, which is low carb/high fat. Medifast or Ideal Protein are two commercial diets that are low carb/low fat. They are ketogenic diets meaning that you eat carbs below a certain level to force your body to derive energy mainly from fat. I think IP uses 30-40g carbs/day whereas Medifast is about 60-70g of carbs/day. Ketosis curbs hunger and cravings since it decreases insulin signals in your body. Insulin is a hormone that regulates energy homeostasis (usage and storage) in response to carbohydrates. Ketosis in the presence of enough protein in your diet may also enhance fat usage and allow you to loose fat more efficiently.

JBeaty, I agree with you and would have thought more carbs would be better since you are active in sports. Carbs and protein are both important to maintain energy.

Maybe by reducing 'carbs' your doctor mean less sugar and pasta? A lot of people use the word 'carb' incorrectly, failing to realize that almost everything we need for a balanced diet and healthy lifestyle is a carb. Other than fat and protein, that's all that's left. Nutrient rich green vegetables, antioxidant packed fruits, protein and fiber rich beans, etc. IMO, the type of carb is more important than the amount of carbs.

This. They have little to no training and you probably do more research into what's current. A trip to Pub Med can show the studies about what really matters in diet. I'd see a dietician/nutritionist or if you exercise...an exercise nutritionist....

What a vague question. There must be some reason your doctor said so, no doctor just out of the blue tells you to go on a diet without a specific reason, what was your visit out? With such little information there's virtually nothing we can help you with.