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Fat Vs Carb: Which Is A Better Diet For Weight Loss?

“Let food be thy medicine and medicine be thy food,” was coined by the father of medicine, Hippocrates.  The study of nutrition and its relationship to the body has been studied for millennia.  In the early twentieth century, the profession of dietitian and nutritionist became recognized and has shaped modern thought on the foods we consume.  Yet, with such a long history, there are still unanswered questions surrounding common problems such as weight loss.  Many today are confused regarding the correct way to obtain weight loss without compromising muscle.  In our day of answers that are available at our fingertips, we often receive mixed messages on such an important topic.

We don’t have to search far to hear people discussing the newest diet.  Messages of “Eat this, don’t eat that”, are everywhere.  Most diets can be placed into two distinct buckets- low-fat or low carb.  One such explanation to this can be linked to the studies conducted over the years. In the later twentieth century, it was discovered that high fat intake had a direct link to heart disease and other chronic conditions.  This discovery led to the advice by professionals to reduce the total fat eaten daily.  Food companies began to echo this recommendation by reducing total fat in their food products.  This caused another problem.  If fat was removed, what could it be replaced with?  The answer was an increase in carbohydrates.  This not only reduced fat but could also reduce the total calories of a food because carbohydrates are less dense than fat.  The problem was solved … or so it seemed.

Unfortunately, obesity and overweight rates did not go down as expected, they actually increased.  CDC data shows a steady increase of obese rates as we moved from the twentieth century to the twenty-first.  This has caused great confusion and further research to take place leading to an increase in diets decreasing carbohydrates instead of fat.  People wondered if all fat was bad and if limiting it really made a difference.  This places us in our modern quandary.  What really works?  Is it the amount of fat consumed that leads to weight gain or is it the carbs?

Pros and Cons of Low Fat Diets

It’s very easy to see something that doesn’t work and get rid of it without trying to investigate why it isn’t working in the first place.  Many times, we may not see some of the benefits it may provide until after the idea is discarded.  Such is the case with low-fat diets.  A broad definition for a low-fat diet is 20-35% of calories consumed coming from fat.  Countless studies affirm and reaffirm the fact that consuming a low-fat diet decreases the risk factors for heart disease, regulates blood sugar, and may aid in weight loss1,2 .  

As scientists delved deeper into the makeup of fats, they quickly learned that not all fats are bad.  Basically, fats can be divided into three different categories- trans fats, unsaturated fats and saturated fats.  Trans fats are formed when the natural chemical structure is altered through a process called hydrogenation.  This process is very beneficial to food manufacturers yet quite unhealthy to the public.  All health professionals agree trans fats have no health benefits whatsoever and should be eliminated from the diet.  

Unsaturated fats are found in foods such as olive oil, avocados, nuts, seeds and salmon.  There are considered the healthiest form of fats.  This category can be broken down further into poly-unsaturated fats or monounsaturated fats.  This distinction is based upon the number of double bonds in its chemical structure.  Poly-unsaturated fats have more double bonds than monounsaturated fats.  The superstar Omega 3’s fall into this category of fats.  Such benefits provided include a reduction of cardiovascular disease, anti-inflammatory properties, and improved brain function.  

The problem comes with saturated fats.  These are found within animal fats and are typically solid at room temperature, such as butter.  Initially, saturated fats were considered the main culprit of heart disease and weight gain.  Foods containing saturated fats were off limits to dieters because it was believed that this would hinder weight loss.  Studies are demonstrating that saturated fats are more complex than originally thought.  It appears that when someone reduces their saturated fat intake and replaces it with carbohydrates, particularly simple sugars, the risk of heart disease increases and weight loss is hampered3.  Some countries around the world trying to fight obesity, have even lifted their restrictions regarding saturated fats due to this updated research3.

Pros and Cons of Low Carb Diets

Low carb diets have many different names.  Diets such as the ketogenic diet fall under this category.  The general guidelines for carbohydrates ranges from 45-65% of the total calorie intake.  For a low carb diet, recommendations can plummet as low as only 5%.  Data proves that this type of diet does promote weight loss and can help regulate blood sugar levels for individuals with diabetes4.  Other benefits include the possible reduction of triglyceride levels5.  

One downside to low carb diets is the vast difference in fat and protein levels in the diet.  Studies demonstrating positive results use 30-35% calories from protein6 .  Studies such as one conducted by The National Institute of Health have demonstrated more effective weight loss and decrease in the risk of developing heart disease when consuming low-carbohydrate diets7.  Reviews of multiple studies (also known as mega-analysis studies) show greater decreases in total cholesterol, LDLs (‘bad cholesterol’) and triglycerides.  It also showed an increase in HDLs, the good cholesterol8.   The positive results were found when healthy fats were consumed in larger amounts and carbohydrates, particularly simple or refined sugars, were reduced.

Of note, it appears that this type of diet should only be used for a short period of time as well.  This differs from the low-fat diet which can be adopted into a lifestyle as is promoted in the Mediterranean Diet.

And the Verdict Is…

Is there really a correct answer to the weight loss question of low-fat or low carb?  The answer is yes.  It actually goes back to very basic nutrition recommendations.  There are fats that are required by the body for a healthy lifestyle.  Carbohydrates are required for health as well.  When aiming for weight loss, fat intake should be moderate, no more than the 30% recommended but not comprised of items such as trans fats.  The majority of the fat should be poly-unsaturated fats.  If consuming a low-fat food item, ensure that the fat replacement is not a refined sugar.  Carbohydrates should also be consumed in the recommended amounts of 40-50%.  These should not consist of refined or simple sugars but should be high in whole grains to provide adequate fiber promoting satiety and regulation of blood sugar levels.  

Yes, Hippocrates was correct, food should be our medicine and medicine our food even when trying to better understand weight loss.   We do not have to wonder what will be the best diet to follow for the most effective weight loss.  Studies show moderation and wise choices are still the key that unlocks the door to weight loss performed in the healthiest way.