By Robert Schinetsky
For decades, dietary fat (namely saturated fat) was considered persona non grata, in that if you wanted to live a long and healthy life free from cardiovascular disease, you limited your intake of fat.
Recently, though, the pendulum has swung the other way, and fat is now the belle of the nutrition ball with carbohydrates being public enemy #1.
And around and around the dietary debate carousel goes. This decade low carb, high fat diets are promoted as the “right” way to eat, while as little as 15-20 years ago, high carb, low fat diets were touted as “the way” to optimize health, performance, stave off chronic disease and lose weight.
So, what’s the truth?
Which diet really is the best one to follow?
Both higher carb, low-fat diets and low carb, high fat diets can work for weight loss, and this has been shown time and time again in research.[1,2,3,4,5] So long as calories and protein intake are controlled for, it really doesn’t matter which diet an individual follows — he or she will lose weight.
That’s because at the end of the day calories reign supreme when it comes to gaining or losing body weight. If you eat more calories than you burn in a given day, you will gain weight. Conversely, if you expend more energy than you consume over time, you will lose weight. It’s simple thermodynamics — calories in vs calories out. Now, you’ll hear proponents for each diet offer reasons why their way of dieting is superior and we’ll explain why they’re both flawed in their logic.
Low-carb zealots have made their living off of making people scared of insulin — the “fat gaining” hormone. According to the low-carb/keto crowd, when you eat carbs, your blood sugar is elevated, and in response, your body releases insulin to shuttle the glucose in your blood to your fat cells. At the same time, when insulin levels are elevated, fat burning is hindered. Therefore, insulin = fat storage not fat burning. However, what’s ignored in this argument is the fact that protein also can stimulate the release of insulin. And, insulin also serves a role in the metabolism of dietary fat. Moreover, insulin actually helps suppress appetite, and it also helps limit muscle protein breakdown (which is especially important when dieting for fat loss).
So, while eating carbs does elevated blood sugar and insulin levels, a high-carb diet doesn’t inherently lead to chronically elevated blood sugar levels, energy swings, or diabetes. And, insulin isn’t the bad guy, either. While it does shuttle nutrients in the body, they don’t go automatically to fat. Insulin transports nutrients into all tissues of the body, including muscle tissue where they can be used for energy. If there is an excess of energy, then insulin will transport the nutrients to adipose tissue for storage.
Now, let’s take a stab at why certain aspects of the high carb, low fat diet marketing material is flawed. Low-fat proponents highlight the fact that dietary fat is very energy dense, as it has nine calories per gram, while carbohydrates and protein contain four calories per gram. Additionally, very little dietary fat is immediately burned for energy in the body, with the vast majority of it going straight to adipose tissue and stored as fat. (Note, this is why some people say that eating fat makes you fat.)
However, like the low carb arguments, this one has its own flaws. While fat does contain more calories than carbohydrates, it tends to be more satiating than carbs on a gram-for-gram basis, which is important when dieting as the more full you feel from your meals the less cravings and hunger pangs you have to deal with.
Furthermore, while your body can store dietary fat in adipose tissue, at the end of the day, if you are in an energy deficit, you will still burn fat and lose weight. So, where does that leave us?
At the end of the day, the best diet for you is the one that includes food that are nutritious and that you enjoy eating. Adherence is the greatest factor in the success of any long-term diet. By this, we mean that if you relish the thought of dining on bacon, eggs, avocadoes, and steak with nary a potato or slice of bread in sight (and this allows you to stay in a calorie deficit), then have at it. On the flip side, if you prefer plates of pasta with marinara, gourmet sandwiches with assorted meats, cheeses, and vegetables, or a simple bowl of pho from your favorite Vietnamese restaurant, that can work too.
So, long as you are able to maintain a calorie deficit, consume enough dietary protein, satisfy your micronutrient requirements, and can adhere to your nutrition plan, it doesn’t really matter whether you go high carb, low fat or high fat, low carb. They both can (and will) work. Some people simply feel more full eating higher fat diets, while others feel better eating a higher percentage of carbs and less dietary fat.
In the end, only you know what your body responds best to, and which manner of diet leaves you feeling more satisfied. Right now it might be low fat, high carb, but 5 years from now it could be just the opposite. Just realize that both styles of eating can work for weight loss. Experiment with both styles of dieting and see which one works best for you!
1. Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial [published correction appears in JAMA. 2018 Apr 3;319(13):1386] [published correction appears in JAMA. 2018 Apr 24;319(16):1728]. JAMA. 2018;319(7):667–679. doi:10.1001/jama.2018.0245
2. Thomson, C. A., Stopeck, A. T., Bea, J. W., Cussler, E., Nardi, E., Frey, G., & Thompson, P. A. (2010). Changes in body weight and metabolic indexes in overweight breast cancer survivors enrolled in a randomized trial of low-fat vs. reduced carbohydrate diets. Nutrition and Cancer, 62(8), 1142–1152. https://doi.org/10.1080/01635581.2010.513803
3. Johnston, C. S., Tjonn, S. L., Swan, P. D., White, A., Hutchins, H., & Sears, B. (2006). Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. The American Journal of Clinical Nutrition , 83(5), 1055–1061. Retrieved from http://ajcn.nutrition.org/content/83/5/1055.abstract
4. Phillips SA, Jurva JW, Syed AQ, et al. Benefit of low-fat over low-carbohydrate diet on endothelial health in obesity. Hypertension. 2008;51(2):376–382. doi:10.1161/HYPERTENSIONAHA.107.101824
5. Hu T, Mills KT, Yao L, et al. Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol. 2012;176 Suppl 7(Suppl 7):S44–S54. doi:10.1093/aje/kws264
6. Franz, M. J. (1997). Protein: metabolism and effect on blood glucose levels. The Diabetes Educator, 23(6), 643-646,648,650-651. https://doi.org/10.1177/014572179702300603
7. Jauch-Chara K, Friedrich A, Rezmer M, et al. Intranasal insulin suppresses food intake via enhancement of brain energy levels in humans. Diabetes. 2012;61(9):2261–2268. doi:10.2337/db12-0025
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