How the Zone Diet works and why dietitians are hesitant to recommend it

• The Zone Diet is a type of anti-inflammatory diet designed to burn fat fast.
• Meal plans on the Zone Diet consist of 40% carbs, 30% protein, and 30% fat.
• The Zone diet bans certain healthy foods that may make it unsustainable long-term.

The Zone Diet is a meal plan where each meal is broken up so that it contains 40% carbohydrates, 30% protein, and 30% fat. This differs from a traditional Western diet because you're eating slightly fewer carbs, more protein, and less fat.

The boost in protein and fewer carbs are meant to help you keep your blood sugar levels stable, reduce inflammation, and lose fat at the fastest possible rate, according to the diet's proponents and founder Barry Sears.

However, some experts are skeptical of the Zone Diet. And while limiting carbs has been shown to help regulate blood sugar levels, there's no evidence that the Zone Diet, specifically, is superior to other fad diets.

How does the Zone Diet work?

The Zone Diet does not exclude any food groups. However, in order to burn fat as quickly as possible, proponents of the diet say that you must reduce inflammation throughout your body.

Therefore, the foods you should and should not eat are based on whether or not they may cause inflammation and blood sugar spikes.

What foods to avoid on the Zone Diet

• Processed grains like white bread, pasta, and rice
• Foods considered high in sugar like sweeteners, desserts, juice, and certain fruits including bananas, cantaloupe, watermelon, mango, and pineapple
• Starchy vegetables like corn, peas, and tubers like potatoes
• High-fat and processed proteins like marbled steaks, hot dogs, and hamburgers

What foods to eat on the Zone Diet

• Certain whole grains like barley and oatmeal
• Low-sugar fruits and vegetables like apples, berries, broccoli, and kale
• Lean protein like turkey, fish, chicken breast, and egg whites
• Low-fat dairy
• The diet also encourages followers to take fish oil and supplements containing fruit and vegetable extracts

Tips to follow the Zone Diet: hand and block method

The Zone diet offers an easy way to remember some of its rules like its hand method. The number 5 — like the five fingers on your hand — represents 3 meals a day, plus 2 snacks, and also reminds you never to go more than 5 hours in between meals.

The Zone diet also uses a block method to help you track which foods to eat and how much of each food. In this method, one block equals:

• 7 grams of protein
• 9 grams of carbohydrate
• Either 1.5 grams of animal fat or 3 grams of vegetable fat

For each meal, the average woman needs to eat 3 blocks of her choice, while men need 4 blocks. Including 2 daily snacks, which is 1 block each, that equates to:

• 11 zone blocks total for women per day
• 14 zone blocks total for men per day

However, depending on your starting point, you may need more. To find out what your particular needs are, the Zone Diet website has a body fat calculator.

Should I try the Zone Diet?

"There's nothing magical about the fact that this diet encourages primarily whole, less processed foods," says Lauren Harris-Pincus, a registered dietician and founder of Nutrition Starring YOU.

Harris-Pincus adds that any nutritious diet will lead to improvements in blood sugar and inflammation and may also help you lose weight. So, you don't have to follow the carbs-protein-fat ratio of the Zone Diet to achieve those results.

It's unlikely that following the diet would cause real harm, says Harris-Pincus, but the bans on certain foods don't seem to make sense health-wise.

"Any diet that discourages consumption of foods known to be beneficial to human health concerns me," Harris-Pincus says, adding that the diet discourages eating many different fruits and whole grains, which — as part of a balanced diet — reduce the risk of diabetes and heart disease.

There has been very little research on the Zone Diet, and the small studies that exist don't live up to all of the diet's claims of improvements in blood sugar, reduced inflammation, or weight loss.

For example, a small 3-week study from 2004 found that people on the Zone Diet showed no added improvement in blood sugar or weight reduction compared with people eating their regular diets.

Admittedly 3 weeks is a short time. However, two other studies found that people who were overweight who followed the Zone Diet for a year did not improve blood sugar levels and only lost about 3.5 pounds.

Insider's takeaway

If the Zone Diet fits with your lifestyle, there is no harm in trying it, says Harris-Pincus.

However, you may want to alter the diet to leave in healthy carbs like whole grains and fruits or opt for a healthier eating plan that's actually recommended by experts like the DASH diet or Mediterranean diet.