Harvard Study Demonstrates That All Calories Are NOT Created Equal

Studies show that calories are not the same and equal.

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.


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

Low-fat diet resulted in the slowest metabolism

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.

Some Issues…

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.

Low-fat and the low-glycemic index diets both had 20% of their calories that comes from protein.

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?

Download RealDose Fat Loss Fast Start Program

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.

Steve Sisskind, M.D.

Hi, I'm Dr. Steve Sisskind, Chief Medical Officer & Founder at RealDose Nutrition.

As a young physician, I struggled because my patients came to me with serious health issues, but I didn't have the right tools to help them. Medical school taught me how to put "band aids" on their symptoms with drugs and surgery, but not how to address the root causes of their problems.

Years later I discovered a better approach... based on the fundamental idea that the power of nutrition can transform your health and vitality. But there's a lot of confusion... What foods should I eat? Which supplements should I take? What does the science say?

I have dedicated my life to answering these questions... And I share this knowledge with you every day here at RealDose Nutrition.

I invite you to connect with me by joining my free private community. I've helped thousands of people and I know I can help you too!

Join the Whole Body Club

Dr. Steve Sisskind is on a mission to help you achieve amazing health and vitality through the power of nutrition. Sign up to get access to his valuable health tips, recipes, videos, and discounts for FREE!


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

Check Also

The 1-step trick to tame your cravings

One subject that comes up a lot around here is how to deal with cravings. …


  1. I am supposing this is the same Harvard that produces graduates that when asked who won the Revolution they answered ” The South ” Anyway, leave it to the Mind Control Educashun Industry to keep us running smoothly [ hampster style ] inside our wheel. I suppose it doesn’t matter what fats – McDonalds and Miracle Whip or organic avocados and raw cashew butter. If you want to lose weight stop all refined foods, wheat, sugar. All meat grass fed and organic for starters. Get you thyroid checked and if your TSH is over 1.9 you are in the danger zone. Read ‘Stop the Thyroid Madness and then read it again and then read it again. The Pharmaceutical Industry WANTS you hypo thyroid and it is an epidemic they will not disclose. By making the ‘ normal ‘ range as high as 6.5 [ TSH ] it artificially lies to 20 % !!!! of the population and effectively keeps them sick and addicted to their expensive medications for high cholesterol, diabetes, depression. weight loss drugs, not to mention heart disease and inflammation related metabolic dysfunction and related ills.They KNOW that all htis could be alleviated by placing the TSH test range to the upper limit of 2.0 and prescribing Natural Desiccated Thyroid or Cytomel which costs about 7.00 a month. The drug industry owns this planet. They own the food industry. They own the insurance companies. They own your doctor. And if you let them, they will own your body and pimp you out to all these clients for 60+ years and leave you in debt for your own funeral.

  2. I get bored easily eating the same things week after week so I tend to eat rather impromptu meals. My caloric intake varies from day to day, as well as the balance but I’m trying to keep it below 1600. This time, however, I go swimming 2 to 4 times a week (depending on my work schedule). At first, the scale didn’t budge for many weeks but I was getting comments about my shoulders and face (the first place weight loss is noticeable for me). Today (hooray) it finally dropped 1 lb from last week. I know that muscle weighs more than fat (and I’m hoping that I have been building muscle mass) but by how much? I’ve seen a size illustration for 5 lbs of fat, but what is the relative size of 5 lbs of muscle?

    • Dr. Steve Sisskind

      Hi Patti,

      Thank you for writing in and for sharing your concerns! Congratulations on the weight loss progress! A pound of muscle will weigh the exact same as a pound of fat. The difference lies between the size. While fat layers are less compressed and are relatively thicker, Muscle fibers are dense and more compact. A pound of muscle is roughly the size of your entire fist while fat layers, when rolled are about twice the size. You dropping your first pound means your body is already responding to the changes you have made. Keep at it and do not stop! Make it a healthy day!

  3. Love all the new studies! The best diet I have done is the fat flush! It’s like I reset my whole body clock and felt better than when a teen! But very restrictive! IT WORKS! I never knew that I could feel so good! But hard to keep up for life! The Minh trampoline she recommends to get lymph system going,, I did not do! But should have! I feel full fat natural is best, and need cortisol direction! I also have very thin hair now, and believe cortisol might be contributing! I love your posts but despise listening to long adds ,, that promise to be short , just to get a sales pitch! I have thought of stopping your info -many times, because it’s frustrating, but I really appreciate the good stuff!

  4. Yes please! Would be very interested in reading guest articles and any other info etc. Thank you,

  5. What worked best for me is writing down my calorie intake and keeping it close to 1400 and 1500 daily and jumping on my mini trampoline four to five nights a week in the privacy of my bathroom. I danced and jumped to music on it. I put it upside down on the tub when not in use. I also found that using half a cup of water to half a cup of 1℅ or 2℅ milk tasted better and was lower in calories than one cup of nonfat milk, even in cereal.(but if u write the calories used as 1 cup of nonfat milk u will be a little more successful sooner.

  6. Caleb Ellingburg

    Yes, please introduce us to other successful nutrition information that you yourself discover or through your friends.

    • Dr. Steve Sisskind

      Hi Caleb,

      Thank you for writing in and for sharing your thoughts with us! I am glad you have found my blogs and posts helpful. I will be publishing more updates soon and do hope they assist you in your journey to better health. Stay tuned! Make it a healthy day!

  7. Oh Yes. please do provide all the new info you find. Just started 100 Days on Real Food with my Kindle reader today. New Book
    recommended by the FoodBabe

Leave a Reply

Your email address will not be published.