Is There an Ideal Macronutrient Ratio for Fat Loss?

image of Healthy eating foods that can be used macronutrient ratio

You might wonder whether diet or exercise is more important for fat loss. Most experts believe that diet is 80% of the weight loss equation and exercise 20%. In other words, it’s hard to out-exercise a poor diet, no matter how intense your exercise routine. What you eat matters and so does your macronutrient ratio!

One worthy change you can make to your diet for better weight control is to eliminate refined carbohydrates and sugar. These dietary components provide little in the way of nutrition and have a negative impact on metabolic health. Once you’ve made these basic changes, you might wonder how to best structure your diet to maximize weight loss. In other words, what is the ideal macronutrient ratio, if there even is one?

If you’re hoping to find the perfect macronutrient composition to accelerate fat loss, research shows you might be disappointed. We’re all a bit different from a genetic standpoint. Some people may benefit more from a diet higher in healthy carbs, especially those who exercise hard, while others, especially people with insulin resistance, thrive best on a diet lower in carbohydrates. So, there isn’t necessarily a macronutrient ratio that’s ideal for everyone. But, based on a recent study, finding an ideal ratio may not be necessary. This study shows you can successfully lose weight on a diet that’s low in carbs OR fat.

Macronutrient Ratio: Low-Fat vs. Low-Carb Diets

A new study carried out by researchers at Stanford University and published in the February 20 issue of Journal of the American Medical Association is shaking up the weight loss world. It shows you can lose weight on a low-carb or a low-fat diet and one isn’t better than the other. What makes this study unique is it involved more than 600 people and the study followed the participants for a full year. Many of the previous studies looking at low-carb vs. low-fat diets and that showed that one approach is better than the other were shorter term and smaller in scope. This study, due to its size and length, has more credibility than the previous studies.

What did the study entail? The healthy, male and female participants were randomly assigned to two groups: low-carb or low-fat. The low-fat group restricted their fat intake to 20 grams per day while the low-carb participants consumed only 20 grams of carbs daily for the first two months and then were allowed to gradually increase their carb and fat intake. After the second month, the low-fat group consumed around 42 grams of fat daily and the low-carb group 97 grams of carbs, on average.

The participants chose healthy, whole food sources of carbs and fat and minimized processed foods and added sugar. Both groups ate a similar number of calories, although the low-carb group ate slightly more protein. At various times, the researchers drew blood and measured various parameters to ensure the participants were sticking to their respective diets. The participants were also screened for genetic variations that might indicate that they would do better on one diet or the other. Previous research suggests that people respond differently to diets based on their genetics. They also measured insulin levels in the subjects, so they could see if those with higher insulin levels, indicating insulin resistance, would respond better to a low-carbohydrate date.

The results? At the one-year mark, the low-carb group lost an average of 13 pounds. The low-fat group did roughly as well, losing almost 12 pounds of weight, on average. What’s more, even subjects who had genetic variations showing they might benefit from one diet over the other or higher insulin levels, lost similar amounts of weight, regardless of the type of diet they were on.

What Can We Conclude?

Based on this large, well-conducted study, whether you choose a low-carb or a low-fat diet to lose weight, doesn’t matter. You can lose weight on either diet. But, don’t take this to mean you can eat anything you want. The participants in the trial limited the amount of processed food and food with added sugar they ate. Cutting back or eliminating these foods is important if you’re trying to lose weight as they’re low on the nutrient-density scale. When you’re watching portion sizes, the foods you eat should be nutrient-dense to lower the risk of nutritional deficiencies. As this study suggests, diet quality is important, whether you choose low-carb or low-fat. The real key may be choosing the one you can stick with.

Although the study suggests the type of diet you choose for weight loss doesn’t matter as long as its high quality, other factors enter into the equation. For example, if you’re pre-diabetic or have reduced insulin sensitivity, a lower carb diet may be better for blood sugar control and for your metabolic health. Another consideration is hunger. Studies show that diets higher in protein tend to reduce hunger better than those lower in this macronutrient. You may find that it’s easier to control how much you eat if your diet is higher in protein.

Another consideration is how physically active you are. If you work out hard and strength train, a low-carb diet isn’t an ideal choice as your muscles need glycogen to help you get through a challenging sweat session. In addition, you need a certain amount of protein and carbs in your diet to stay out of a catabolic state. A very low-carb diet won’t replenish muscle glycogen as effectively and could cause your workout performance to suffer, especially if you do high-intensity exercise.

Also, in the study, researchers counseled the participants on how to eat mindfully and encouraged them to put what they learned into practice. For example, they were asked to eat slowly and avoid munching when distracted. Adopting a more mindful approach to eating is beneficial, regardless of the type of diet you adopt.

The Bottom Line

If you’re trying to lose weight, make sure the diet you eat is nutrient-dense, made up of whole foods, and adopt a more mindful approach to eating. Ultimately, this approach will help you lose weight, regardless of whether you’re eating low-carb or low-fat.




Examine.com. “Low-fat vs low-carb? Major study concludes: it doesn’t matter for weight loss”
JAMA. 2007 Mar 7;297(9):969-77.
Diabetes Obes Metab. 2013 Jan;15(1):87-90. doi: 10.1111/j.1463-1326.2012.01668.x.


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