9 reasons why low carb diets actually work

low-carb-diets-workScientific studies have proven low-carb diets are a safe and effective strategy for weight loss.

People who follow a low-carb diet lose 2 to 3 times more weight than the standard low-fat diet still recommended by many health professionals. (1, 2)

Cutting carbs is the best route to trimming off excess pounds, and you can also expect improvement in other important health markers. (3)

Blood sugar, triglycerides and blood pressure usually drop significantly, and HDL cholesterol (the good kind) climbs. (4, 5, 6, 7)

Much of the fat lost on low-carb diets comes from the belly area as well as the liver; getting rid of this dangerous visceral fat in the midsection results in lower levels of the inflammation known to contribute to a higher risk of chronic diseases. (8, 9)

Low-carb diets have been shown to be particularly beneficial for people who suffer from type 2 diabetes and metabolic syndrome.

Experts enjoy debating the mechanical reasons for weight loss on low-carb diets, and it’s clear there are multiple processes involved. (10)

We’ll take a look here at the reasons experts believe low-carb diets work so well.

1. Insulin Levels Decrease

The main hormone regulating fat storage and blood sugar levels is insulin. It instructs fat cells to hold onto stored fat, as well as producing more.

It also sends the orders for other body cells to pick up blood sugar (glucose) and use it for fuel. Low-carb diets cause immediate and dramatic reductions of insulin. (11, 12)

2. The hypothesis is that once insulin levels fall, fat isn’t locked away in cells and can be utilized for energy.

The late Dr. Atkins, along with other experts like science and nutrition writer Gary Taubes, claim that lower insulin levels are the main reason low-carb diets work, but this theory is not shared by many researchers in the field of obesity.

3. Water Weight is Released Quickly in Initial Stages

When people begin a low-carb diet, water weight drops drastically during the first week or two. Here’s what happens in the body:

  • Insulin decreases and the kidneys excrete excess sodium, lowering blood pressure. (13)
  • Glycogen levels decrease, because carbs are stored in this form; glycogen binds water in the liver and muscles, so lower levels contribute to the release of water.

These processes don’t take place when higher levels of carbs are present in the diet, even when calorie intake is restricted.

While some use this as an argument against the effectiveness of low-carb diets, releasing excess water isn’t a bad thing, and as mentioned above, fat also decreases, especially in the belly area.

4. Protein Intake Increases

For those following a low-carb diet, foods high in carbohydrates are often replaced with protein foods.

Eating more eggs, fish and meat reduces appetite and boosts metabolism, as well as increasing the amount of muscle mass in the body; more muscle mass means more calories are burned around the clock. (14, 15)

The metabolic advantage of eating more protein is believed to be a big part of the effectiveness of a low-carb diet.

5. A 2012 study showed that energy expenditure in subjects following a low-carb diet increased by an average of 250 calories daily, which amounts to about an hour of moderate exercise. (16)

A separate trial suggested higher levels of protein, as opposed to lower levels of carbs, was actually the catalyst for this change. (17)

Some experts believe part of this significant change in metabolism is due in initial stages to the inefficiency of a bodily process called gluconeogenesis, which transforms protein into glucose for fuel. (18)

After a few days of very low carbohydrate intake, ketones start replacing glucose as fuel for the brain, which is more efficient. (19)

6. Low-Carb Diets Shift Attention from “Food Rewards”

Many fattening junk foods are automatically cut out of low-carb diets, including sugar and sweet drinks, pizza, white bread and pasta, and French fries.

Variety alone has been shown to increase calories in the diet, and the prospect of “rewarding” ourselves with tasty treat foods has great impact on the amount we eat. (20, 21)

Decreased variety and the removal of processed foods from the diet is likely a huge factor in the success of low-carb diets.

7. Reduced Appetite Leads to Lower Caloric Intake

Basically, when we’re not as hungry, we don’t eat as many calories. (22)

Many nutritional experts believe this aspect is the single most influential factor in why low-carb diets work.

8. Studies comparing low-fat diets with low-carb diets highlight the fact that caloric restriction were imposed on those following a low-fat plan, while low-carb subjects ate as much as they wanted and still lost more weight. (23)

Increased protein intake is a major player in appetite reduction, but ketosis may also have strong effects on appetite. (24)

Studies also indicate low-carb diets have positive effects on ghrelin and leptin, the hunger hormones. (25)

9. Long-Term Results for Low-Carb Diets

Test participants following low-carb diets have realized stellar results in losing weight and improving vital health markers in study after study, but a year or two up the road, the numbers tell a different story.

The gap between those who lost weight eating low-fat diets and those who took off extra pounds by cutting carbs closes as time passes, and long-term success rates are actually quite similar.

It appears this is most likely due to the fact that people have a hard time sticking to a low-carb diet over time, and usually go back to eating foods high in carbohydrates, including refined grains, processed foods, sweet drinks and other choices not included in low-carb plans.

This scenario is not limited to low-carb diets; long-term weight loss studies indicate most people don’t stick with any diet for years. (26)

The biggest argument against low-carb diets is that if people are allowed to eat as much as they want, the calories in/calories out model is being violated.

However, when the mechanisms at work are examined, it’s clear this isn’t true. Appetite reduction and metabolic advantages combine to decrease the amount of calories being consumed.

Low-carb diets essentially make calorie reduction automatic through these processes, which short circuits the biggest problem with dieting: hunger.

Summary: For fast weight loss without hunger, low-carb diets are more effective than low-fat diets, and have the added benefit of improving vital health markers and positively altering metabolism so you burn more calories while taking in less.


  1. http://onlinelibrary.wiley.com/doi/10.1111/j.1464-5491.2007.02290.x/full
  2. http://www.nejm.org/doi/full/10.1056/NEJMoa022637
  3. http://onlinelibrary.wiley.com/doi/10.1111/j.1467-789X.2012.01021.x/abstract
  4. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892194/
  5. http://www.ncbi.nlm.nih.gov/pubmed/19439458
  6. http://www.ncbi.nlm.nih.gov/pubmed/16409560
  7. http://www.ncbi.nlm.nih.gov/pubmed/19099589
  8. http://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-1-13
  9. http://www.ncbi.nlm.nih.gov/pubmed/21367948
  10. http://www.nature.com/ejcn/journal/v67/n8/full/ejcn2013116a.html
  11. http://www.ncbi.nlm.nih.gov/pubmed/16403234
  12. http://www.ncbi.nlm.nih.gov/pubmed/20107198
  13. http://ajprenal.physiology.org/content/293/4/F974
  14. http://www.ncbi.nlm.nih.gov/pubmed/15466943
  15. http://www.ncbi.nlm.nih.gov/pubmed/11838888
  16. http://www.ncbi.nlm.nih.gov/pubmed/22735432
  17. http://ajcn.nutrition.org/content/early/2015/01/14/ajcn.114.091769.abstract
  18. http://www.ncbi.nlm.nih.gov/pubmed/19640952
  19. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC543577/
  20. http://www.ncbi.nlm.nih.gov/pubmed/11393299
  21. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3319208/
  22. http://www.ncbi.nlm.nih.gov/pubmed/17228046
  23. http://press.endocrine.org/doi/full/10.1210/jc.2002-021480
  24. http://onlinelibrary.wiley.com/doi/10.1111/obr.12230/abstract
  25. http://www.nature.com/ejcn/journal/v67/n7/full/ejcn201390a.html
  26. http://www.ncbi.nlm.nih.gov/pubmed/19828901
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