“I don’t get it,” she said with frustration. “Why don’t diets work?” My client was sincerely confused why, after 20 years of trying, she still didn’t feel like she knew how to feed herself. And she STILL hadn’t lost the weight.

And what about all those “other people” who succeeded? Was there something just totally wrong with her? If you, too, wonder why diets never really worked for you, this post will explain the hidden realities weight loss programs often fail to mention before you start.
reason #1 diets don’t work: because size diversity exists
Fat people exist. Some folks are bigger, genetically speaking. This has been, and will always be, true. There is nothing pathologically wrong with being bigger, just as there is nothing pathologically wrong with being smaller – in and of itself. Health is way more complex than that and is mostly driven by social determinants, rather than individual behaviors.
Health research doesn’t even consider the idea that some folks are meant to be bigger.
As a result, we position our evidence-based health care around creating thin bodies as a means to health, instead of working toward the wellbeing of the individual. Many individuals have known this to be counterproductive to health, at best. My clients report skipping doctor’s visits to avoid the shame.
I would attempt to explain size diversity theory myself, but it’s already been done masterfully for me by this video put forth by the Association for Size Diversity and Health:
In my group coaching programs, I lead a discussion about this video to help clients understand that their bodies are individual. From there, we work toward defining health beyond size, and this often helps them to stop blaming themselves for diets not working. By working through my No Guilt Framework, they can see the reality: some of us are meant to be bigger – and that’s okay.
The key takeaway from this video? Weight loss research is deeply flawed. It assumes:
- all bodies should, and can, achieve a “normal BMI” – this is false
- simply achieving a “normal BMI” leads to health – also false
- BMI is built of a sample of white males and was never intended for use in individual health care
- and, research often fails to account for the known effects of racism, poverty, and exposure to weight stigma, among other social determinants of health
It is difficult to accept health recommendations hinged on the flawed BMI, especially since we have data to show people in the “overweight” BMI category actually live longest. Practicing health enhancing behaviors like: not smoking, staying active, reducing alcohol, and eating fruits and vegetables improves health outcomes at any size, including higher BMI categories.

reason #2 diets don’t work: because metabolic adaptation is a thing
Do you remember your first diet? You may recall weight loss felt easier and faster back then. This is because your body had never been on a diet before. Another way to say this? Your first time dieting is your first time starving. Your body didn’t know any better.
As you succeed in weight loss, the body starts to learn you are in calorie deficit. From there, your body’s brilliant design helps you from starving. Here’s what happens:
- fat loss decreases a hormone called leptin, which drives hunger and lower basal metabolic rate (to preserve energy!)
- after a certain point of weight loss, you need to consume fewer and fewer calories to continue to drive, and maintain it
It does not matter if you are “on keto” or if you are intermittent fasting. The body will respond this way, eventually. And because dieting beyond your set-point weight is difficult to maintain without feeling excessive hunger, loss of control eating, and urgency around food – many regain the weight back.
If you attempt to lose weight again, your body behaves almost as if it is “allergic” to the dieting process. The body remembers your weight loss attempt from before and protects you from perceived starvation by slowing your metabolism down; because that’s what a diet is – starvation. This is also why restriction is the most probable cause of loss of control binges. Your body will literally override your senses to get you to eat, if it really has to.
Research following up with The Biggest Loser game show contestants seems to validate this theory. After “transformative weight loss” and “the best” support – many saw permanent reductions in their metabolism as a result of their past dieting attempts. In my group program, we work to STOP choosing diets that will continue to damage metabolism, and instead, help the body heal from a lifetime of chronic dieting through Intuitive Eating.
reason #3 diets don’t work: because mental health matters
I want you to think about your last diet. What were the rules? Was it a certain number of calories? Or perhaps, removal of certain food groups?
Every diet, even the most flexible ones, have rules. These rules often reinforce rigid black-and-white thinking associated with disordered eating, anxiety, and depression. When working with clients in my coaching programs, I offer clear skills to combat food guilt that emerges from “good” and “bad” thinking around food. This often leads to immediate improvements in mental, emotional, and social health.
Diets often do not work because forcing your body to become smaller often means giving up mental and emotional wellbeing. My No Guilt Framework goes beyond seeing mental health as important as physical health: I show you how to love and enjoy food without guilt or loss of control. Personally, I think satisfaction from food is an important part of culture and brings meaning to life. I believe all women, especially those in bigger bodies often told they can’t enjoy food, deserve to experience food joyfully. To me, a diet does not work if it means giving up your ability to connect with others and feel free around food.
By allowing an “all foods fit” approach, my clients learn to eat enough, until satisfied, without binges or guilt.
most “success” you see is a snapshot
Most medical research studies last only around 6 months. More robust studies may go on for 18 months to 2 years. As a Registered Dietitian who previously worked in medical weight loss research as an interventionist, I can first-hand back up what the meta-analyses point to: weight loss is possible, but even with the strongest interventions and support, most regain within 2-5 years.
So when you see your friend from high school putting up her side-by-side photos on Instagram, remember to affirm for yourself: most diets fail. Anyone suppressing weight below their natural set point range through dietary restriction will experience physical and mental fatigue sticking to their plan over time. That’s not the fault of the individual, of course: diet’s just don’t work. It’s best in the long run to learn to be okay with, and listen to, your body.
so if diets don’t work: now what?

The fact that diets don’t work isn’t a call for despair. It’s an invitation to learn to listen to YOUR body for the very first time.
This post includes a few of the many skills I offer through my No Guilt Framework. Each individual will find different skills helpful at different times, and this post is by no means an exhaustive list of why weight loss has been challenging for some. My philosophy is this: create a positive relationship with your body and food, and your weight will fall where it is meant to be.
I offer group and private coaching programs that help you create a plan and practice these skills with the focus and consistency you need to FINALLY be okay with your body. Apply for coaching and I’ll meet with you to describe how you can go from feeling completely stuck in the diet cycle to feeling free and peaceful around food in 3 months, just like my clients do.