What Is the Endomorph Diet and Could It Do More Harm Than Good?

Westend61/Getty

Health and fitness are not one-size-fits-all—and this is especially true for diets and eating styles. While keto might work wonders for some people, intermittent fasting might be the go-to for others, and still, others might steer clear of anything with restrictions, period (not a bad idea, if you ask us).

One diet that seems to be getting some attention (albeit, it's not entirely new at all) is the endomorph diet, which is all about eating based on your "body type." If you think this sounds a bit, err, archaic, you're not alone (*raises hand*). Here, experts weigh in on the pros and cons of the endomorph diet and if there's any validity to this concept at all.

What is an endomorph?

During the 1940s, researcher and psychologist William Herbert Sheldon classified the human body into three categories or somatotypes based on their body composition (yep, even though that's a fluid thing that can change) and build (your skeletal frame or bones). Sheldon reported that his research suggests that body types are inherited and, thus, reaching weight loss and fitness goals might require an individualized plan. (If you're thinking, 'well, no duh', we're with you.)

To that end, before you read ahead we wanted to give a friendly and important (!!) reminder to take these "body types" and his theories with a grain of salt. It's impossible to know someone's metabolic rate just by looking at them—and the same is true for their ability to gain or lose weight or muscle.

The three body types, according to Sheldon:

Ectomorph: long, lean body with a fast metabolism, which makes it difficult to gain muscle and weight

Mesomorph: athletic, muscular, and can gain or lose weight easily

Endomorph: larger bone structure but shorter in stature with a slower metabolism, making it hard to lose weight (On that note, can you really speed up your metabolism?)

As a psychologist, Sheldon's focus was on how these somatotypes relate to personality traits and temperaments. While novel for the time, his research has since received criticism as he claimed causation rather than correlation among other missteps, according to Niket Sonpal, M.D, adjunct professor of clinical medicine at Touro College of Osteopathic Medicine in New York City. Some experts also question the validity of using somatotypes to make claims about a person's health, especially since there isn't ample data to back up Sheldon's body type descriptions, says Dr. Sonpal.

"I would say that these ways of looking at body types are very antiquated and from a clinical standpoint have very little bearing on the health of the individual," he adds.

What is the endomorph diet?

As you may have guessed, the endomorph diet is the plan developed specifically for the endomorph body type. Speaking generally, Sheldon described the endomorph body type, as tending to have a smaller upper body with narrow shoulders and waist and curvy hips and thighs, according to says Phil Catudal, NASM-certified personal trainer and author of Just Your Type: The Ultimate Guide to Eating and Training Right for Your Body Type. Endomorphs also tend to have higher fat percentages relative to their muscle mass, says Basima Williams, D.O., a functional medicine-certified primary care and weight management physician at PALM Health in St. Louis, Missouri.

So it's likely not surprising that the endomorph diet tends to focus on weight and fat loss. But the endomorph diet plan could also be used as a guideline for boosting strength, gaining muscle, and following a more balanced, whole-foods-focused eating plan instead, if you aren't interested in the weight loss aspect. (See also: 8 Ways to Increase Your Metabolism.)

How does the endomorph diet supposedly work?

Unlike many other diets out there, the endomorph diet does not limit how many calories you consume per day. It does recommend a near-equal split of macronutrients, with 30 percent carbohydrates, 35 percent protein, and 35 percent fats. To put that into perspective, the average American diet is almost 50 percent carbs, 15 percent protein, and 35 percent fat, according to the Centers for Disease Control and Prevention (CDC). However, if you're using the plan for weight loss, your daily allotment still needs to put you in a caloric deficit, says Catudal. This is where an expert may be helpful to make realistic recommendations about food for your health and goals. (See also: Exactly How to Cut Calories to Lose Weight Safely)

The endomorph diet is also lower in refined carbs like white rice and pasta. Instead, carbohydrates primarily include vegetables with smaller amounts of unrefined, high-fiber starches, like quinoa, oats, or beans, says Williams. Essentially, the endomorph diet encourages taking in more protein, fiber, and healthy fats while lowering carb intake. Sound familiar? That's because the endomorph diet is reminiscent of another popular eating plan: the paleo diet. While both diets make major cuts on carbohydrates, the endomorph diet allows for high-fiber grains, legumes, and dairy. (Related: The Paleo Diet for Beginners.)

Is there validity to any of this?

The classifications should be used as a guide to give clues into why you might be struggling to reach certain goals, not as an assumption of how your body should look or perform, says Catudal. There are a variety of unofficial quizzes online [read: proceed with caution] that asks you to consider prompts such as, "my body tends to: 1) carry more muscle, 2) carry more fat, or 3) has a hard time gaining either," to help determine your "body type".

What's more, Sheldon's body type descriptions are incredibly oversimplified and ignore the multitude of factors that can impact someone's ability to alter their body composition. Not to mention that body composition—the proportion of fat versus non-fat mass, which includes muscles, bones, organs, and water—varies from person to person and between body types.

The ratio of muscle and fat isn't the only consideration for determining metabolism either. Rather, metabolism takes into account a multitude of components such as your musculoskeletal system (your structure or "build") and endocrine system (your hormones). These components, along with genetics and healthy habits, play a huge role in determining your body composition, says Catudal. However, in very general terms: the more muscle, the faster your metabolic rate; the more fat, the slower. (Related: How Hormones Affect Your Metabolism)

If you're still interested in exploring the endomorph diet, consider talking with your doctor to identify your body composition, says Dr. Sonpal. Unlike generic body type guidelines from appearance alone, a doctor (or registered dietitian) can help you develop an even more individualized plan to reach your specific health and fitness goals that look beyond just a number on a scale.

So, should you try the endomorph diet?

While you might find short-term success, both Williams and Dr. Sonpal say they are uncertain about the long-term sustainability of any diet that restricts certain foods. The other important concern with the endomorph diet is the lack of individual assessment, says Dr. Sonpal. It doesn't take into account a person's goals, genetics, exercise routine, lifestyle, or any pre-existing conditions, he adds.

There's also something inherently self-critical about labeling your body based on incomplete research from several decades ago. While he's had patients lose weight on the endomorph diet, Dr. Sonpal attributes this to their ability to make healthy changes to exercise and diet, which may or may not have anything to with the endomorph diet or their body type.

Additionally, while the diet in itself isn't harmful (fiber and protein are good for you, after all) it could restrict your thinking about food and healthy eating in the future, says Dr. Sonpal. Instead, Williams prefers using the SMART method—which stands for Specific, Measurable, Achievable, Realistic, and Timely—to identify health and fitness goals and the necessary steps for accomplishing them. People who meet with functional dieticians and physical trainers take a whole-person approach to health, and develop a long-term, consistent routine, have the most success, says Williams. How you approach food and exercise, be it to lower body fat, increase muscle mass, or simply feel your absolute best is personal—and because of this, can't be defined solely by a body type.

Bottom line: Stop thinking about what mold you fit in or what "type" you are. Eat to fuel your goals and your happiness.