low carb diets work

Do Low-Carb Diets Work?

Written by: Kelley R. Hill, MSN, RN-BC

In a Nutshell

  • The low-carb diet was introduced by Dr. Robert Atkins in the 1960s
  • Low-carb diets resurfaced and gained popularity in the 2000s for rapid weight loss
  • Many professional healthcare organizations have spoken out against low-carb diets

The low-carb diet, hugely popularized in 2003 , is still popular and utilized for rapid weight loss. The gist of the diet is that you heavily restrict your carbohydrate intake to no more than 20g daily, consuming mostly protein and fat.

Poorly conducted, short-term studies at the turn of the century showed that low-carbohydrate diets initially produced more weight loss than conventional low calorie, low fat regimens. Quality studies conducted within the last decade, however, show that low-carb diets don’t produce significant long-term weight loss, aren’t sustainable over years (or even months), and if eating too much unhealthy food lead to serious health problems.

The acceptable macronutrient distribution range (AMDR) was developed in 2002 to express dietary recommendations within the context of a complete diet. The acceptable macronutrient distribution ranges are 45–65% of your daily calories from carbs, 20–35% from fats, and 10–35% from protein.

Sustainability is Why Low-carb Diets Rarely Work

  • The body is forced to use fats rather than glucose as its main fuel source, leading to ketosis.
    • This leads to side effects of nausea, dizziness, confusion and inability to concentrate, headache, fatigue, constipation, and bad breath. Ketosis also leads to metabolic dehydration – the body’s consumption of its own water stores – which is what produces the drastic initial weight loss.
  • Over a long period of time the diet becomes boring and unpleasant – not delicious.
    • While eating all the meat and fat you want may seem really dreamy, the fact remains that after a while it loses its luster
  • Health problems mandate that the diet be abandoned.
    • Chemical and mineral imbalances that threaten all body cells (tissue, organ, bone, everything).
    • Oxidative stress on heart muscle that can be debilitating or even fatal.
    • Increases the risk of lung cancer and intestinal cancers.
    • Increased uric acid leading to joint pain and gout.
    • Increased calcium leading to kidney stones and osteoporosis.
    • Permanent loss of kidney function in persons with already reduced kidney function (which is 1 in 4 Americans)
    • Wildly vacillating blood sugar and insulin levels that can cause organ dysfunction, tissue damage (like the eyes), and even death.

Authorities Warn Against It

There are a number of preeminent health organizations that have spoken out against low-carb dietsThe general consensus is that the quantities of food low-carb diets recommend are unacceptable, regardless of the phase of the diet.

  • American Heart Association (AHA)
  • American Cancer Society (ACS)
  • American Diabetes Association (ADA)*
  • American College of Preventive Medicine (ACPM)
  • American Dietetic Association
  • United States Department of Agriculture (USDA)
  • World Health Organization (WHO)

*It is worth noting that the American Diabetes Association (ADA) recently revised its Standards of Medical Care document to include low-carb diets as a safe and effective option for people with insulin-dependent type 2 diabetes. The ADA still refrains from recommending low-carb diets to those who also have renal disease, and for those who are not insulin-dependent, simple portion control and healthy food choices are preferred.

Professionals agree that there can be a substantial initial weight loss with low-carb dieting, even in persons who have not had success with more balanced diet approaches. No one is arguing that point.

What professionals argue is that:

  • The weight loss is greatly temporary.
  • In 6-12 months, any other perceived health benefits greatly disappear.
  • The diets remain imbalanced in all phases and do not include education on proper nutrition to support sustainability.
  • They do little in the short-term, and nearly nothing in the long-term, to improve existing conditions; and cannot prevent onset of new ones.
  • The potential health risks are too devastating.


You should always consult with your physician, and ideally a nutritionist or registered dietician (RD), before radically changing your diet or eating habits. Especially if you have existing health conditions, are on prescription medications, or are pregnant or breastfeeding.

Low-carb diets do produce greater weight loss than conventional diets for the first 6 months, but the differences are not significant at one year. At 12 months, the effects on weight reduction and any improvements in cardiovascular health largely disappear.

Serious, potentially permanent, and potentially fatal health problems have been associated with low-carb diets.


Recommendations are based on inconsistent or limited quality evidence, mostly small trials and industry-funded research, and greatly supported by consensus only. The fast and considerable weight loss with low-carb dieting often occurs, but claims around both weight-loss and additional health benefits have not been demonstrated beyond a short period of time.


Low-carb diets – while perhaps superior in achieving initial rapid weight loss – are neither as effective nor as safe as standard diet recommendations, conventional diets, and multiple other diets that have surfaced in the last few years.


  1. Systematic review of popular diet programs | The BMJ
  2. A Randomized Trial of a Low-Carbohydrate Diet for Obesity | NEJM
  3. The ketogenic diet all grown up-Ketogenic diet therapies for adults - PubMed (nih.gov)
  4. The Atkin’s diet controversy (nih.gov)
  5. Optimizing Protein Intake in Adults: Interpretation and Application of the Recommended Dietary Allowance Compared with the Acceptable Macronutrient Distribution Range - PubMed (nih.gov)
  6. Atkins Diet: Expert Reviews | US News
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