40-30-30 Diet Results, Pros/Cons, and Macro Calculator (2024)

What is the 40-30-30 Diet Plan?

The 40-30-30 diet is a macronutrient-based approach to nutrition popularized by the Zone Diet program. American biochemist Barry Sears developed the Zone Diet in the late 1980s to combat “diet-induced inflammation.”

The basic principle of the 40-30-30 diet is that 40% of your calories come from carbs, 30% from protein, and 30% from fat. This macronutrient ratio is slightly lower in carbs and significantly higher in protein than the standard American diet (50-15-35)¹.

Science Behind 40-30-30 Diet

Scientific studies do not support all of the health claims made by Sears. For example, there is no evidence that this diet reduces inflammation or improves physical performance².

However, some of the 40-30-30 diet concepts are based on sound science. And it could help improve your health and body composition in certain situations.

40-30-30 Diet Blood Sugar Control

The 40-30-30 diet appears to have a modest impact on blood sugar or insulin levels. And researchers suggest that such a diet could help control blood glucose in people with type 2 diabetes³.

The reason is that the reduced carbs and increased protein resulted in decreased 24-hour glucose concentration compared to a high carb, low protein diet. In addition, reducing starchy carb sources in favor of fibrous vegetables also played a role in blood sugar control.

40-30-30 Diet Pros & Cons

So far, we’ve mostly talked about the health benefits of the 40-30-30 diet, like improving insulin sensitivity and preserving lean muscle. And there are other benefits, such as more flexibility compared to low-carb diets.

However, the 40-30-30 diet has downsides as well. Most notably, the Zone Diet recommends 1,200 calories daily for women and 1,500 calories for men. That makes it a very low-calorie diet and could result in significant muscle loss and metabolic damage in some individuals.

In addition, this diet plan requires you to understand and count macros, which may be more work than some are willing to do. Lastly, the 40% carb target isn’t tailored to your individual activity level, body, or fitness goals.

Pros

• Easy to follow concept
• Relatively flexible food choices
• Well balanced nutrient intake
• High protein supports lean muscle
• Don’t have to eliminate carbs
• May improve blood sugar control in people with type 2 diabetes

Cons

• Does not prescribe a personalized calorie target
• Requires knowledge of macronutrients in food
• Must count macros
• May be too many carbs for sedentary people
• May be too few carbs for highly active people
• Not tailored to your body or lifestyle
• Beneficial effects are not as pronounced in men or those with healthy blood sugar levels

40-30-30 Diet Guidelines

The foundation of the 40-30-30 diet is the macronutrient ratio of 40% carbs, 30% protein, and 30% fat. And you could hit these targets with any food, like an IIFYM meal plan.

However, the Zone Diet prescribes certain foods to enhance blood sugar control and weight loss. Here are the general guidelines for following this diet to a T.

• 40% Carbs: About 2/3 of each meal should consist of fibrous veggies and a little fruit. Avoid starchy carbohydrates like potatoes and corn.
• 30% Protein: Roughly 1/3 of each meal should consist of lean protein from fish, eggs, poultry, beef, or low-fat dairy.
• 30% Fat: The remaining 1/3 of each meal should consist of monosaturated fat like olive oil, avocado, or almonds.

40-30-30 Macro Meal Plan Example

At this point, you might like the idea of the 40-30-30 diet but don’t know where to start. So let me walk you through an example of how to find your macros for this meal plan.

For this example, let’s say that you need to eat 2,000 calories per day to progress towards your fitness goals. All you need to do from here is multiply 2,000 by the various macro percentages.

Remember, you can divide a percentage by 100 to make it a decimal with which you can multiply. So your 40% carb intake would be 2,000 x 0.4 = 800 calories. Protein and fat are 2,000 x 0.3 = 600 calories each.

Now to convert from calories to grams. Carbs and protein have 4 calories per gram, while fat has 9 calories per gram. So we divide the calories by these numbers.

That’s 800 ÷ 4 = 200 grams of carbs. 600 ÷ 4 = 150 grams of protein. And 600 ÷ 9 = 67 grams of fat.

Enter your actual daily calorie intake to see your 40-30-30 macro targets in grams.

40-30-30 Diet FAQ

Next, I’ll answer some of the most common questions surrounding the 40-30-30 diet.

Is 40-30-30 a good macro ratio?

In general, 40% carbs, 30% protein, and 30% fat is a decent starting point for people just getting into counting macros. And it represents a significant improvement over the high carb, low protein diet most people follow.

That said, there is no single best macronutrient ratio for everybody. And the 40-30-30 diet might not be ideal for your body or circ*mstances.

What foods can you eat on the 40-30-30 diet?

You can follow the 40-30-30 diet by eating any foods that result in hitting the macro targets at the end of the day. But, of course, you’ll get better results if you stick with mostly healthy, whole foods.

On the strict version of the 40-30-30 diet (Zone Diet), no food is technically off limits. But it encourages you to avoid eating starchy carbs and replace them with vegetables instead.

Here is a list of foods recommended on the Zone Diet.

Carbohydrates

• Fibrous veggies like lettuce, broccoli, peppers, tomatoes, mushrooms, squash, onions, and more
• Low-glycemic fruits like berries, apples, plums, and more
• Grains like oatmeal and barley

Protein

• Lean red meats like beef, lamb, and wild game
• Poultry like chicken and turkey
• Fish and shellfish
• Egg whites
• Low fat milk, cheese, and yogurt

Fat

• Oils like olive, canola, and sesame
• Nuts like peanuts, cashews, almonds, or pepitas
• Nut butters
• Avocados