Low-Carb Diets most Successful for Weight Loss, multiple Studies find.

Are you trying to lose weight? Are you already counting calories, you are constantly hungry and still you can’t get any results? It might be that you are eating the wrong kind of food that sabotages your weight loss.

Research studies find that losing weight is less about reducing calories and more about eating the right kind of food.

But haven't we been told that a calorie is a calorie no matter where it comes from? Even though it might defy our sense of logic in the first place, but our bodies do not run like machines where energy input equals energy output.

Our bodies are controlled by hormonal responses.

For instance, 100 calories from carbohydrates will have a different impact on your body as 100 calories from protein or fat, due to the hormones your body releases.

Low-carb vs. Low-fat studies

In a study from 2004, overweight men and women were randomly assigned to a very-low carbohydrate diet where about 70% of calories came from fat or to a low-fat diet where the majority of calories came from carbs. [1]

The individual resting metabolic rate was determined, and everyone was assigned to a diet with a caloric deficit of 500 calories. The men consumed each diet for 50 days whereas women consumed the diets for approximately 30 days.

Both, men and women on a very low carbohydrate diet lost on average almost twice the amount of body weight compared to the men and women on a low-fat diet. (Figure below)

 
Mean decreases in body mass, total fat mass, trunk fat mass, and lean body mass in men who consumed a very low-carbohy- drate ketogenic (VLCK) diet (n = 8) or a low-fat (LF) diet and in women who consumed a VLCK (n = 7) and LF (n = 6) diet.

Mean decreases in body mass, total fat mass, trunk fat mass, and lean body mass in men who consumed a very low-carbohy- drate ketogenic (VLCK) diet (n = 8) or a low-fat (LF) diet and in women who consumed a VLCK (n = 7) and LF (n = 6) diet.

 

In another two years trial, 300 people were set on either a low-fat diet, a low-carb diet or a Mediterranean diet. The researchers aimed to keep the calories equal between each diet (which of course is hard to monitor in a two years experiment on humans, so let’s not keep that for granted).

Nevertheless, the results are clear. The Mediterranean diet and the low-carbohydrate diet were more successful in losing weight. So, it is either that you burn more fat even if you consume the same amount of calories or it is just easier to stick to these diets. [2]

 
Weight Changes during 2 Years According to Diet Group. [2]

Weight Changes during 2 Years According to Diet Group. [2]

 

An old study from 1956 eliminates all guessing to what diet is the most successful for weight loss. [3]

Obese volunteers were assigned to diets in which the calorie intake was kept constant at 1000 calories a day and 90 % of it was provided in turn by carbohydrate, fat, or protein.

To ensure an accuracy of the study, the volunteers were stationed in a hospital and the scientist exluded everyone who deviated from the strict meal plan.

They switched the diets after 5-9 days to further ensure that the results are not entirely dependent on body type.

The weight loss was the greatest when 90% of the calories came from fat, second best weight loss was seen with the 90% protein diet, but the 90% carbohydrate diet barely showed any weight loss.

Daily changes of weight of patients on 1000-calorie diets of body-weight different composition (mean of 5-9 days on each diet).

Daily changes of weight of patients on 1000-calorie diets of body-weight different composition (mean of 5-9 days on each diet).

There are many more studies showing a similar outcome [4-19]. However, the question arises why this would be the case. A variety of factors play into account, including the effect of different food components on our hormones (studies regarding this topic are explained in this video) and our metabolism.

A metabolic boost on low-carb

A recent study from 2018 found that cutting back on carbs can boost the metabolism. [20]

The study included 164 overweight participants who were split into three groups and were assigned to a low-carb, moderate-carb, or a high-carb diet for 20 weeks. The diets were controlled for protein and calories and the energy expenditure (total number of calories the participants were burning) was determined after 10 and 20 weeks.

The researchers found that after 10 and 20 weeks those on a low-carb diet burned about 250-300 calories more per day than those on a high-carb diet.

 
Change in total energy expenditure [4]

Change in total energy expenditure [4]

 

Take Home Message:

Low-carbohydrate diets are more successful compared to low-carb diets due to their potential to boost the metabolism.

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References:

  1. Volek et al., Comparison of energy-restricted very low-carbohydrate and low-fat diets on weight loss and body composition in overweight men and women, Nutrition and Metabolism, 2004

  2. Shai et al., Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet, N Engl J Med, 2008

  3. Kekwick and Paran, CALORIE INTAKE IN RELATION TO BODY-WEIGHT CHANGES IN THE OBESE, The Lancet, 1956

  4. Bazzano et al., Effects of Low-Carbohydrate and Low-Fat Diets: A randomized trial, Ann Intern Med, 2014

  5. Foster, et al. A randomized trial of a low-carbohydrate diet for obesity. New England Journal of Medicine, 2003

  6. Samaha, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. New England Journal of Medicine, 2003

  7. Sondike SB, et al. Effects of a low-carbohydrate diet on weight loss and cardiovascular risk factor in overweight adolescents. The Journal of Pediatrics, 2003.

  8. Brehm BJ, et al. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. The Journal of Clinical Endocrinology & Metabolism, 2003.

  9. Aude YW, et al. The national cholesterol education program diet vs a diet lower in carbohydrates and higher in protein and monounsaturated fat. Archives of Internal Medicine, 2004.

  10. Yancy WS Jr, et al. A low-carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia. Annals of Internal Medicine, 2004.Volek

  11. Nickols-Richardson SM, et al. Perceived hunger is lower and weight loss is greater in overweight premenopausal women consuming a low-carbohydrate/high-protein vs high-carbohydrate/low-fat diet. Journal of the American Dietetic Association, 2005.

  12. Daly ME, et al. Short-term effects of severe dietary carbohydrate-restriction advice in Type 2 diabetes. Diabetic Medicine, 2006.

  13. McClernon FJ, et al. The effects of a low-carbohydrate ketogenic diet and a low-fat diet on mood, hunger, and other self-reported symptoms. Obesity (Silver Spring), 2007.

  14. Gardner CD, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study. The Journal of The American Medical Association, 2007.

  15. Dyson PA, et al. A low-carbohydrate diet is more effective in reducing body weight than healthy eating in both diabetic and non-diabetic subjects. Diabetic Medicine, 2007.

  16. Westman EC, et al. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus. Nutrion & Metabolism (London), 2008.

  17. Keogh JB, et al. Effects of weight loss from a very-low-carbohydrate diet on endothelial function and markers of cardiovascular disease risk in subjects with abdominal obesity. American Journal of Clinical Nutrition, 2008.

  18. Volek JS, et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids, 2009.

  19. Brinkworth GD, et al. Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 months. American Journal of Clinical Nutrition, 2009.

  20. Ebbeling et al., Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial, BMJ, 2018

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