Ask the Dietitian: What’s the Best Carb, Protein and Fat Breakdown for Weight Loss?

Ask the Dietitian: What’s the Best Carb, Protein and Fat Breakdown for Weight Loss?

Elle Penner, MPH, RD
by Elle Penner, MPH, RD
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Ask the Dietitian: What’s the Best Carb, Protein and Fat Breakdown for Weight Loss?

Between the different diet trends and conflicting research findings, it seems we’re more confused than ever about what and how much to eat, particularly when it comes to the three key macronutrients: protein, carbohydrates and fat. While there’s no one magic combination that will make the pounds melt off, you can optimize your diet for weight loss by adjusting the composition of your calories.

WHICH MACRO SHOULD YOU ADJUST?

When it comes to choosing what to eat more of and what to cut back on for weight loss, consider first what you want to achieve. The goal of losing weight is to reduce fat stores while preserving, or even adding, lean tissue — what we refer to as muscle.

Carbohydrates are an important source of fuel for our muscles during exercise and are the only source of energy for our brain and red blood cells. Fat is equally important, playing major roles in everything from brain function to cell structure, but if you’re trying to lose weight, it may not hurt to trade some carbohydrates and/or fat calories for a boost in protein. Calorie for calorie, protein has the most metabolic benefits for weight loss: it increases satiety, stimulates energy expenditure and preserves muscle, which unfortunately is used for energy along with fat during weight loss.

HOW MUCH SHOULD YOU ADJUST?

For most, it is safe to adjust carbohydrate, protein and fat consumption to optimize the diet for weight loss. You may find it beneficial to trade a percentage of your calories from carbohydrates or even fat, for protein calories.

As a jumping off point, let’s review the current recommendations for carbohydrates, protein and fat, as well as MyFitnessPal’s default goals for these nutrients:

CURRENT RECOMMENDATIONS

The 2015-2020 Dietary Guidelines for Americans recommends eating within the following ranges:

  • Carbohydrates: 45–65% of calories
  • Fat: 25–35% of calories
  • Protein: 10–30% of calories

Also worth mentioning here is the Recommended Dietary Allowance (RDA) for carbohydrates, which is 130 grams per day. This number is based upon the amount of carbohydrates (sugars and starches) required to fuel an adult’s brain, red blood cells and central nervous system. This is important because if we do not get enough carbohydrates from our diet, the body will break down protein (which it can turn into glucose) to maintain blood sugar levels and fuel the brain and red blood cells.

MYFITNESSPAL’S DEFAULT GOALS

MyFitnessPal’s current default goals distribute calories as follows: 50% from carbohydrates, 20% from protein and 30% from fat.

To help you visualize some modest modifications, here’s a table summarizing a couple of options for safely cutting back on calories from carbohydrates and fat while increasing protein intake to optimize the diet for weight loss:

For those primarily interested in cutting calories from carbohydrates, a 1,200-calorie diet with 45% of calories from carbohydrates would provide 135 grams of carbohydrates, thus meeting the RDA of 130 grams. Go below that and it becomes incredibly difficult to hit your daily fiber goal (which also helps with satiety) and you may feel more sluggish during workouts. Hypothetically speaking, a 1,300-calorie diet with as few as 40% calories from carbohydrates (below the recommended minimum) would still meet the RDA for carbohydrates.

If you’re currently using MyFitnessPal’s default goals and want to trade some carb calories for protein, the 45:25 carbohydrate-to-protein ratio may be a good place to start.

THINK ABOUT QUALITY

While there’s no one magic ratio for everyone, you may find that making some modest adjustments to macronutrient intake can help your long-term weight loss efforts. Feel free to experiment but remember: The quality of the protein, fat and carbs you eat are just as important as the quantity. Here are a few things to keep in mind as you adjust your macros:

1. When it comes to carbohydrates, the more complex the better. Complex carbohydrates like vegetables and whole grains, contain fiber which has a beneficial impact both on satiety and blood sugar. Put those on your plate instead of highly refined or simple carbohydrates and sugary treats. The Essential Guide to Carbs offers some healthy options.

2. Lean protein offers muscle-sparing benefits with very few calories from fat. Check out the Essential Guide to Protein for information on plant-based protein sources as well as lean cuts of meat, poultry and fish to stock up on.

3. Fats have many benefits ranging from satiety to brain health–especially those rich in omega-3s. Skim over the Essential Guide to Fat if you’re looking for some heart-healthy options.

Note: Modest changes in macronutrient intake can be beneficial for weight loss; however, these tweaks may not be appropriate for everyone, particularly those with diabetes, kidney disease or other diseases affected by diet composition. As always, it’s best to check with a registered dietitian or doctor before making these changes, particularly if you have medical concerns.

About the Author

Elle Penner, MPH, RD
Elle Penner, MPH, RD

Elle is a nutrition and wellness writer, recipe developer, blogger and nutrition consultant whose favorite things include her camera, carbs and quality time with her toddler. For more from this busy mama, check out Elle’s lifestyle blog or connect with her on Instagram, Pinterest and Facebook.

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