A new study published in the Journal of the American Medical Association pitted three popular diets against each other… challenging the notion that a calorie is just a calorie.
The focus was to study the impact of the diets on energy expenditure. That is, which diet would help people burn the most calories per day.
The researchers also measured hormone levels, insulin sensitivity, blood fats and enzymes (you will see why this is important later).
Battle of the Diets
Low-fat: Focused on whole grain products, and a variety of fruits and vegetables. 60% of calories came from carbohydrates, 20% from fats, and 20% from protein.
Very low-carb: Similar to Atkins. 10% of calories came from carbohydrates, 60% from fats, and 30% from protein.
Low-glycemic index: Emphasized beans, fruits and vegetables, while reducing the amount of grains and starchy vegetables. 40% of calories came from carbohydrates, 40% from fat, and 20% from protein.
Participants were randomly rotated between each of these diets for one month at a time. The actual consumed calories consumed were identical… it was just the ratios (as mentioned above) that varied.
|Test Diets During Weight-Loss Maintenance1|
|Nutrient||Low Fat||Low Glycemic Index||Very Low Carbohydrate|
distribution, % energy
|Dietary intake, mean (SD)|
|Carbohydrate g/d||310.4 (1.7)||205.1 (3.3)||50.1 (1.2)|
|Glycemic Index||67.7 (2.5)||32.9 (3.2)||28.4 (9.0)|
|Glycemic load g/d||185.1 (8.6)||51.1 (6.3)||3.9 (2.2)|
|Fat, g/d||46.5 (0.3)||90.2 (4.3)||133.4 (2.7)|
|Saturated||12.8 (0.5)||22.4(3.7)||47.8 (8.4)|
|Monounsaturated||15.3 (2.2)||40.0 (5.8)||47.7 (7.1)|
|Polyunsaturated||15.7 (2.4)||22.3 (5.3)||22.0 (7.4)|
|Protein, g/d||104.8 (0.6)||105.5 (2.0)||151.5 (1.1)|
|Fiber, g/d||30.3 (2.8)||32.8 (1.8)||11.2 (2.0)|
|Cholesterol, mg/d||140.3 (12.2)||280.1 (173.1)||978.1 (329.7)|
|Sodium, mg/d||2546 (379)||2657 (329)||2646 (718)|
******Detailed Breakdown of Diet Plan Differences*********
And The Winner Is…
At first glance, the winner was the very low-carb diet. When participants followed this diet, they BURNED 325 more calories a day than the clear loser (the low-fat diet).
Let’s put this in perspective. There are 3,500 calories in a pound, so a person eating the very low-carb diet would lose an additional pound every 11 days versus a person eating the low-fat diet. Over a year this would be over a 33-pound difference.
But not so fast! The very low-carb diet worked in the short term… but there were problems.
The very low-carb group saw significant increases in the stress hormone cortisol (the hormone that causes belly fat). Over the long term elevated cortisol, according to the study’s authors, “may promote adiposity, insulin resistance, and cardiovascular disease, as observed in epidemiological studies.”
The very low-carb group also showed increased levels of C-reactive protein (a marker for inflammation and a possible risk factor for heart disease). We know that over time, high levels of inflammation can also lead to the inability to burn fat.
More About the Loser… The Low-Fat Diet
As mentioned before, the low-fat diet resulted in the slowest metabolism. Even worse, when following this diet, participants demonstrated lower levels of good cholesterol and increased triglyceride levels.
So not only was this diet less effective for weight loss or maintenance… it was simply less healthy.
The Happy Compromise
The study authors referred to the third diet (low-glycemic index) as the “Happy Compromise.” This diet burned 125 more calories per day than the low-fat diet.
However, it burned 200 less calories than the very low-carb diet.
But the good news is that this diet did not increase cortisol, inflammation or triglyceride levels and it did not lower good cholesterol.
And additionally, the study reports that participants had an easier time adhering to this diet than the other two options.
While the study results are fascinating, I think it is clear that more head-to-head research is needed, as there seemed to be some confounding variables.
The first variable I noticed was between the low-fat and the low-glycemic index diets. Both had 20% of their calories coming from protein (which I think may be a bit low)… So the difference was the low-glycemic diet basically doubled the fat content of the low-fat diet by taking away from the carbohydrate content.
That would have been fine, but they also changed the TYPE of carbs the participants consumed. By replacing a significant portion of grains and starches in the low-fat group with non-starchy vegetables in the low-glycemic group… participants were able to avoid the insulin spikes that we know slow down metabolism and lead to an unhealthy hormonal cascade.
So I would have liked to see the type of carbohydrates remain consistent across groups.
I would also have liked to see the protein content remain consistent across all three groups as well.
So What is The Best Diet?
After I read this article, I went back and re-read the RealDose Fat Loss Fast Start Program because I am always open to new information.
I did not find anything in this study which would cause me to make any changes, although I certainly would make them if any information contradicted our program.
By the way, you can download the Fat Loss Fast Start Program right here. It might be a good time for a refresher.
The carbohydrates we recommend do not cause insulin spikes, and they are healthier than the carbohydrates used in any of the plans tested, as we totally eliminate grains and starches (except on your cheat day).
We also recommend more protein and fewer carbohydrates than the “Happy Medium” diet. And the Fat Loss Fast Start Program is 100% dedicated to lowering cortisol and inflammation.
Open for Feedback
Ever since we started RealDose almost a year ago, I have had the pleasure of meeting many experts in the fields of fitness and nutrition.
And I have found that some of them have alternatives to my plan which may or may not be more effective for different people at different times.
Some of them are getting pretty amazing (and healthy) results with their clients.
So I am curious, would you like me to introduce them to you via this blog with guest articles? If so, please let me know below in the comments section.
Also, I’d like to know which types of diets you’ve tried in the past and what your results were. Did you lose weight? Did you gain it back?
How did you feel while on the diet?
Did you discover any type of food or meal or have an “aha” that made the diet easier for you?
Your comments could help your fellow RealDose readers succeed going forward, so I encourage you to share.
Lastly, of course, I’d love to hear any thoughts, feedback or questions you might have about what I’ve shared today.
Thank you so much, and I wish you luck.
Steven Sisskind, M.D.
1. Ebbeling CB, Swain JF, Feldman HA, et al. Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance JAMA. 2012;307(24):2627-2634. doi:10.1001/jama.2012.6607