How Atkins 40® Works and the Science Behind It

Carbs and fat are your body’s two sources of fuel. A low-fat diet is high in carbs, so when you eat more carbs than your body needs it stores them as fat. Atkins is an effective diet that transforms your metabolism from one that stores fat into one that burns fat. High-carbohydrate diets raise blood sugar, which in turn signals the body to secrete more insulin—you wind up with more fat on your body and a “sugar burning” metabolism. The Atkins diet restricts foods that are known to raise blood sugar and insulin. Limiting carbohydrates forces your body to use fat for energy rather than sugar.

The classic Atkins approach, which has been renamed Atkins 20®, is the traditional four-Phase program starting with Induction at 20 grams of Net Carbs per day. In addition, Atkins has decided to offer another option, with more flexibility and more food choices, called Atkins 40®.

On Atkins 40®, you begin with 40 grams of Net Carbs a day and move up progressively from there as you get closer to your goal weight, while still burning fat for fuel. In a nutshell (and yes, you can eat nuts from day one on Atkins 40!), Atkins 40 helps you make a variety of food choices from a selection of vegetables, nuts/seeds, a variety of fruits, whole grains, legumes, as well as dairy, including whole Greek yogurt and cheeses. Atkins 40 also focuses on portion control, and emphasizes nutrient-dense carbohydrates. Added sugars are still a no-no.

Here are some things to consider before you jump to Atkins 40 so that you can choose the approach that works best for you:

Stick with Atkins 20® if:

  • You have more than 40 pounds to lose
  • You are pre-diabetic or diabetic
  • Your waist circumference is higher than 40 inches for men, 35 inches for women
  • You are content with food choices being re-introduced gradually, in pre-defined order
  • You are seeing positive results with Atkins 20 (“If it isn’t broke, don’t fix it!”)

Move to Atkins 40® if:

  • You have less than 40 pounds to lose
  • You are not pre-diabetic or diabetic
  • Your waist circumference is less than 40 inches for men, 35 inches for women
  • You are pregnant or nursing
  • You are currently on Atkins 20, and looking for more variety in food choices

Here’s what else you need to know about Atkins 40®:

Each day you have:

  • Approximately 15 grams of Net Carbs that come from high-fiber Foundation Vegetables
  • Remaining 25 grams of Net Carbs the can be chosen freely from the expanded acceptable foods list (Greek yogurt, fruit, nuts, whole grains and legumes)
  • 3 to 4 six-ounce servings of lean protein
  • 2 to 4 servings of healthy fats throughout the day
  • 6 to 8 glasses of water
  • A daily multi-vitamin

The Science Behind Atkins 40®

Atkins 40® is backed by 31 scientific studies, which demonstrate that most people can begin to burn fat for fuel with 40 grams of Net Carbs per day. Here are links to the studies, if you are interested in learning more about the science behind Atkins 40®:

Ballard 2013:

Bazzano 2014:

Paoli 2013:

Ruth 2013:

Saslow 2014:

Tay 2014:

Walsh 2013:

Brehm 2003:

Brehm 2005:

Danzinger 2005:

Dashti 2003:

Dashti 2004:

Ebbeling 2012:

Forsythe 2008:

Iqbal 2010:

Nickols-Richardson 2005:

O’Brien 2005:

Sharman 2002:

Sharma 2004:

Siegal 2009:

Sondike 2003:

Stern 2004:

Velhorst 2010:

Volek 2000:

Volek 2002:

Volek 2003 :(4 weeks)

Volek 2004: (8 weeks)

Volek 2004: (2 years)

Volek 2009:

Volek/Forsythe 2010:

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