Keto, Intermittent Fasting, Atkins, low-fat, Paleo, Whole30 — you’ve probably heard of one or more of these common weight loss diets. Although you can lose weight on these diets, they are, in fact, unsustainable for weight loss or weight management in the long run. Diets, not to be mistaken for normal eating habits, are often necessary to improve biomarkers for people at risk for or in recovery from diseases. They’re also necessary for other health conditions such as gluten or lactose intolerance. But, more often than not, that’s not how they’re used. Over the last few decades, dieting has found its way into popular culture. Fad diets have gained popularity with the rise of social media and the portrayal of skinny as the ideal body image. As a consequence, people often develop a negative relationship with food and become restrictive with their intake. But food shouldn’t be the enemy! Even though the abundance of diet and nutrition information can be overwhelming, the best place to start your sustainable weight loss journey is by buying whole foods. Not limiting or restricting food groups helps, too. Besides eating whole foods, listen to your body’s natural hunger cues and stop eating when you feel satiated to maintain a healthy, positive relationship with food. 

Let’s discuss some of these fad diets and why they’re unsustainable for long-term weight loss.

Why Keto is Unsustainable

Let’s debunk one of the biggest fad diets of the moment — the keto diet. Dr. Katz, founding director of the Yale University Prevention Research Center and president of the True Health Initiative, emphasizes that losing weight fast by using a severely restricted, unbalanced diet inevitably leads to even faster weight regain (1). And the keto diet is just that — characterized by a high-fat and low-carbohydrate intake — it’s a severely restricted and unbalanced diet. 

What is keto anyways? Well, your body’s primary source of energy is glucose, which we get from breaking down carbohydrates and sugars. By removing carbs from your diet you are depriving your body of the fuel it needs. Our brain requires a constant delivery of glucose to function, and luckily, our body has a mechanism in place to provide that energy — even when we don’t. This mechanism is called ketosis, and it involves the burning of fat in the liver to make ketones that can be used as fuel. With the keto diet, this mechanism is continually triggered, and that’s not ideal. Ketosis in our ancestors took place during temporary bouts of food shortages or starvation — they were not trying to diet. Ketosis should be reserved for its biological function and not used as a method for dieting unless it’s for medical purposes (like epilepsy).

Healthy Low-Carb vs. Low-Fat Diet

To provide evidence to support the statement that no one diet is perfect for weight loss, the Stanford Prevention Research Center conducted the DIETFITS study. In the DIETFITS study, researchers compared two common diets — healthy low-carb and healthy low-fat. Both diet groups were instructed to maximize vegetable intake, reduce consumption of added sugars, refined flours, and trans fats, while focusing on whole foods that were minimally processed, nutrient-dense, and prepared at home whenever possible (3). After 12 months, there was no significant difference in weight loss and BMI between the two groups, emphasizing that neither of these diets is better than the other for weight loss. 

Whole Food Diet

A diet rich in whole foods is not only sustainable for weight loss, it’s also sustainable for the environment. Eating foods close to the form they are in when they come from the ground is the basis of following a whole food diet. You’ll be consuming natural sugars, simple and complex carbohydrates, and large amounts of fiber. All while avoiding artificial ingredients, flavors, food coloring, and the like. Examples include eating grilled chicken instead of chicken fingers or eating an orange instead of orange juice. These choices allow you to reap the benefits of all the fibers, phytochemicals, and nutrients found in whole foods. A diet rich in whole foods results in fewer nutrient deficiencies when compared to the Standard American Diet which is high in processed foods, refined sugars and carbohydrates, and fats. 

The following research supports a diet rich in whole foods.

In the BROAD study, participants with heart disease, obesity, or diabetes were assigned to either a whole food, plant-based diet supplemented with Vitamin B12 or a normal care diet. Participants were asked not to count calories and to eat until they felt satiated. Even with no restrictions on calories, which is common in weight-loss studies, the participants who followed a whole food, plant-based diet had significant reductions in BMI and weight. In contrast, the control group on a normal care diet experienced no significant changes in BMI (4). Additionally, in a random crossover trial of hyperlipidemic women, shifting from a refined-food diet to a phytochemical-rich diet of whole and unrefined foods significantly lowered saturated fats and increased polyunsaturated fats (5). Polyunsaturated fats are healthy fats that help lower LDL cholesterol (bad cholesterol) — they’re a staple in the Mediterranean Diet (fish and walnuts). Other healthy fats include monounsaturated fats found in extra virgin olive oil.

When it comes to weight loss, the best diet all-around is a whole food diet, which can be referred to as a way of life. Slowly transitioning to a whole food diet by making one healthy swap at a time can help you reach your goal and contribute to a lifestyle that is more sustainable for your weight and overall health. 

Written by Megan Huff

Reviewed by Kelly Powers, MA, RDN, a Registered Dietitian Nutritionist who takes a holistic approach to nutrition and health. Kelly is a recipe developer with a food blog highlighting whole foods, simple recipes, and her life in San Francisco. She’s the creator of Weeknight Dinners, a weekly meal plan program that helps users get back in the kitchen and feed themselves well.

Frequently Asked Questions

Q: Do carbs make me gain weight? 

A: Excess consumption of anything can result in weight gain. With that being said, carbs and sugars, just like protein and fat, can contribute to weight gain as excess carbs and sugars are converted to fatty acids which are stored in adipose tissue. 

Q: Is white or wheat bread better for me?

A: Wheat bread and whole grain breads are the better options as they are unrefined, meaning they retain their nutrients. They’re also higher in fiber. Additionally, they have a lower glycemic index, meaning that they are digested slower and prevent an immediate spike in blood glucose.

Q: Why can’t I just drink orange juice instead of eating oranges?

A: You can drink orange juice if you’d like, but it’s also important to know that a whole orange retains all of its nutrients and fiber, making it slower on digestion than juice. The juicing process strips whole foods of their nutrients and concentrates the sugars, leading to a spike in blood sugar after consumption. Orange juice actually contains more carbohydrates (from fruit sugars) than eating a regular orange.