Only 4 out of 60 women in a major study hit their weight loss goal—but here’s the surprising part: even though they all lost weight and got healthier, half were still disappointed. Can you guess why?
What You Will Learn in This Post:
Why Expectations Matter:
Setting realistic goals can make you feel better and stay motivated. Unrealistic goals can make you feel like you’ve failed—even when you’re doing great!
Why Weight Loss Slows Down:
Learn how your body naturally defends its weight, why plateaus happen, and how your appetite and metabolism play a big role.
How to Focus on Your Best Weight:
Discover how to aim for a weight that’s healthy, enjoyable, and sustainable instead of chasing an “ideal number.”
In a study of 60 women, each set weight loss goals ranging from their 'dream weight' to their 'disappointed weight'—the lowest weight they’d still consider progress. They followed a strict diet, lost weight, and gained health benefits. But here’s the twist: only 4 reached their goal weight, none hit their dream weight, and half didn’t even meet their 'disappointed weight.'
Why does this happen? It’s not failure—it’s biology. Our bodies have a built-in survival system, shaped over thousands of years, designed to fight against weight loss. It was designed in a time when it was hard for our ancestors to find food. This defense mechanism explains why weight loss can plateau, even with our best efforts. Scientists can predict what most weight loss journeys will look like because of this system, and understanding it is the first step to setting realistic expectations.
So, let’s dive into this fascinating weight loss defense system and explore how shifting our perspective can help us approach weight management in a way that’s freeing, realistic, and sustainable
Your Appetite System: The Weight Regulation System
Your weight is managed by an ancient system in your body called the appetite system, or the weight regulation system. This system includes three key parts of your brain that control appetite and metabolism:
The GateKeeper (deep in our brain): Keeps track of our hormones & energy balance.
The GoGetter (middle layer of the brain): Drives you to seek out and eat food.
The Sleepy Executive (outer layer of the brain): Helps with decision-making and self-control.
These systems work together to regulate your weight. When you lose fat, the GateKeeper in your brain recognizes the change and responds by lowering your metabolic rate (how many calories you burn) and increasing your appetite. This makes the GoGetter push harder, driving you to eat more.
These changes explain why weight loss usually follows a predictable pattern. Weight loss starts off strong, slows down over time, and eventually stops. Scientists call this the shape of human weight loss because it’s so common. This will happen for you. This should be our expectation.
Why Does Weight Loss Slow Down?
Scientists like Kevin Hall and Scott Kahan have studied why weight loss slows over time and reaches a plateau. To understand this, let’s follow the journey of Kathy, a woman who weighs 90 kg (198 pounds) and starts her weight loss program.
Before Weight Loss
Before starting, Kathy was eating about 2,600 calories a day and burning the same amount, so her weight stayed stable. Her body was in balance—calories in equaled calories out.
Starting Weight Loss
To begin losing weight, Kathy reduced her calorie intake to 1,800 calories per day, creating an 800-calorie deficit. This calorie reduction is what kickstarted her weight loss.
1. Appetite Increases
Kathy’s appetite began to increase. Even though she started eating 1,800 calories per day, her brain (the gatekeeper and go-getter) began driving her to eat more. By three months, she was consuming about 2,200 calories per day—400 more than she planned! By six to nine months, her calorie intake increased further to 2,400 calories per day.
2. Weight Loss Stops
By the six- to nine-month mark, Kathy’s calorie intake matched her calorie output of 2,400 calories per day. At this point, her weight loss stopped because she was no longer in a calorie deficit.
This pattern—starting strong, slowing down, and eventually plateauing—is typical of most weight loss journeys.
Why Does Appetite Increase So Much?
Appetite is how many calories your brain thinks you need to regain lost weight. As the GateKeeper senses fat loss, it activates the GoGetter to increase appetite and drive you to eat more.
Here’s how Kathy’s effort changed over time:
At the start: She was eating 1,800 calories per day while her brain wanted her to eat 2,600. This meant she was eating 800 calories less than her brain thought she needed.
At three months: Her brain wanted her to eat 3,000 calories per day, but she was eating 2,200. She was still eating 800 calories less than her appetite demanded, but her weight loss slowed because she was eating more than she did at the start.
At six to nine months: Her brain wanted her to eat 3,200 calories per day, but she was eating 2,400. Again, her effort remained the same (try not to eat 800 calories more), but her weight loss stopped because her intake and metabolism were balanced.
Even though Kathy’s effort stayed the same, trying not to eat 800 calories her brain wanted her to eat, the balance between her calorie intake and her metabolism stopped her weight loss.
The Challenge of Sustaining Weight Loss
The final graph shows why sustaining weight loss requires ongoing effort. To keep the weight off, Kathy needed to continue eating fewer calories than her brain wanted—long into the future.
This is why it’s important to start a weight loss program with a realistic plan. If you begin with a level of effort you can’t sustain, it will be harder to maintain your progress. Instead, aim for a sustainable level of effort that works with your lifestyle over the long term.
What Is Your Best Weight?
When you’re doing your best—eating as healthily as possible and staying active in a way you can maintain—your weight will land at what we call your best weight. This is the weight your body naturally reaches when you practice healthy, sustainable habits.
Your best weight is not a specific number on the scale—it’s the weight your body can maintain when you’re living your healthiest, most balanced life.
Understanding the Weight Loss Plateau
Now that you understand how your body responds to weight loss, it’s clear why most people plateau around the six- to nine-month mark. At this point, calorie intake increases to match calories burned, and weight loss stops.
But remember: this doesn’t mean you’ve failed. Your body is simply following its natural systems. By focusing on sustainable behaviors and setting realistic expectations, you can reach and maintain your best weight for the long term.
An Invitation
Here is your invitation regarding the concept of BEST WEIGHT:
I ask you to consider discarding the concepts of target weight, ideal weight or goal weight.
In their place now is BEST WEIGHT. You can think of BEST WEIGHT as a three-part question.
Would you consider your path forward in weight management to be figuring out the most moderate amount, the least overall number of calories you can take in?
While still enjoying your life and maintaining a loyalty to the things that you enjoy, such as food and drinks, friends and family, socialization and celebration?
At a level of effort that is sustainable, livable and maintainable, and not a level of effort above this?
Do the above three things and then you will discover where this lifestyle softly lands you.
In this scenario you work on finding your 1) most modest, 2) yet enjoyable, and 3) sustainable lifestyle, and then you stand back and let your brain and body “tell you” where your best effort lands you.
In the above scenario there are two competing processes:
1) your brain defends your former weight while 2) you defend your BEST WEIGHT.
Many people at this point will ask “does the brain ever give up trying to return you to your original higher weight—does it ever let up in its effort eventually? After all, does it not prefer you to be at a healthier weight?” Unfortunately, at this point we have no evidence of the brain letting up in either increased appetite or decreased metabolic rate.
You will read repeatedly in this blog that overweight and obesity is a real medical condition that is primarily genetically conferred, progressive and centred in the brain.
These concepts are very well illustrated here. Genetics determines the degree to which your brain defends against weight loss; the degree of increased appetite and the degree of decreased metabolic rate. Yes, this means that weight loss results will necessarily be unique to you.
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