Low-fat, Low-carbohydrate or the Mediterranean Diet – Which is best?

I get asked the low-fat versus low-carb diet question a lot.  Which is better?  The Australian Dietary Guidelines recommends a diet based on eating lots of whole grains, veggies, fruit, some meats and low-fat dairy.  Previously, we had the Atkins diet and now we have the Paleo diet.  The American Dietary Guidelines even recommends the Mediterranean  diet for improved health outcomes, as well as the same guidelines Australia promotes.  So, what is best for weight loss and what is best for our health?

I’ve looked at some interesting studies and I’ll tell you what I’ve found.  I’ll elaborate below, but in a nutshell, the low-carb diet does seem to come out on top, followed closely by the Mediterranean diet, especially for metabolic syndrome symptoms. 

Long-term, the Mediterranean diet seems to be easier to maintain, so I guess that’s the key answer to this question.  From reading these studies, it seems everyone can have improved health outcomes with any of the three dietary styles listed in the title of this post, but you must be able to maintain that diet long-term, and make it a way of life.  It also comes down to your own personal health goals.  Are you looking for fat loss?  Do you want to improve your heart health?  Do you have insulin resistance?  Because I have such a passion for improving the health of women with PCOS, I’m going to focus on fat loss and insulin resistance for this post.

Low-carb versus Mediterranean and low-fat diets 

A study in the New England Journal of Medicine performed a two year study on participants who followed one of these three diets.  The group who followed the low-carb diet lost nearly 145% more weight compared with the group following the low-fat group.  This same low-carb group were the only group to have significant improvements in their long-term blood glucose levels (HbA1c) but, the group following the Mediterranean diet plan had the most improvement in their fasting blood glucose levels.  The group following the low-fat diet plan, had an increase in their blood glucose levels.  This is exactly what we don't want to happen for people with insulin resistance or diabetes!  Women with PCOS have insulin resistance so this study is important for your health too!

Weight changes during the 2 yr study

Changes in cholesterol & TGs

This study also showed the low-fat diet performed the worst for other health markers too.  Not only did it provide the least amount of weight loss, and actually worsened the risks from insulin resistance by raising fasting blood glucose levels, it showed the least improvement for LDL-cholesterol, HDL-cholesterol, triglycerides and the ratio of total cholesterol to HDL-cholesterol - the greatest improvement in this ratio was from the low-carb group (20%). Inflammation only improved in the Mediterranean and low-carb diet groups. There is heaps of new evidence now suggesting inflammation could be related to heart disease and stroke. 

What is really interesting to note about this study is both the low-fat diet and the Mediterranean diet groups were on a restricted calorie intake (1500 Calories for women and 1800 Calories for men), but the low-carb diet group were not restricted on how much they could eat.  This is significant because hunger is often a reason for people abandoning dietary changes.

More and more evidence is pointing toward the successes of eating a low-carb diet.  As I mentioned in an earlier post, Australia's largest research body, the CSIRO, have just completed a three year study on two different diets to improve the blood glucose of people with Type 2 Diabetes (T2DM).  One diet was the traditional recommendation of high unrefined carbs with low-fat and the other diet was low-carbs with high protein and monounsaturated fats.  As you probably know, a symptom of PCOS is insulin resistance which can affect stable blood glucose control and increase the amount of insulin released by your pancreas.  One of insulin's roles is to store glucose as body fat.  The study conducted by the CSIRO found the participants on the low-carb diet had better blood glucose control, with less spikes and lows.  There was also an average medication reduction of 40% with the group who ate the low-carb diet. Women with PCOS are commonly taking the same type 2 diabetes medication to help with insulin resistance so this study is very relative to PCOS sufferers.   

The low-carb versus low-fat diet is a hot debate right now.  An eight year study of nearly 50,000 women showed there was absolutely no benefit to eating a low-fat diet. Did you understand what I just said?  This study showed NO BENEFIT to eating a low-fat diet.  That doesn't mean go straight to your nearest convenience store and chow down on a packet of chips and an ice-cream or two.  What this means is you do not need to be afraid of full-cream dairy or healthy fats from avocados.  Processed foods are still high in sugar, salt, refined carbohydrates and trans fats, so we really want to avoid these "foods".

So, it seems recent evidence does point to dietary lifestyles such as low-carbohydrate diets or the Mediterranean Diet can provide better health outcomes than low-fat diets can provide. The best option for you is the one that suits your lifestyle so that  you can adopt your new dietary habits for life.  Ultimately, whether you choose the Mediterranean diet or a low-carb diet, or somewhere in between, the secret to achieving your health goals really boils down to commitment.  It isn't always easy staying on track but I hope this information helps you reach your goals.

Cheers for now

Annie