The Science of Weight Loss: What Actually Works?

Today, we're diving into a topic that is both deeply personal and complex—weight loss.

Let’s face it: weight loss can stir up strong opinions, confusion, and frustration. My goal in this post is to clear up the basics, explain how I help my clients achieve sustainable fat loss, and hopefully give you a practical, science-backed starting point for your own journey.

Why Is Weight Loss So Difficult?

We’re in the middle of a global obesity epidemic. In the U.S. alone, over 42% of adults are obese, with about 9% falling into the severely obese category. If we include those who are simply overweight, we’re talking about two-thirds of the adult population.

Obesity isn't just a cosmetic issue—it’s linked to chronic conditions like cardiovascular disease, diabetes, certain cancers, and also contributes to emotional struggles such as depression and low self-worth.

Understanding Energy Balance: The Foundation of Weight Loss

Weight gain only happens when you're in a positive energy balance. This means you’re consuming more energy (calories) than you're burning.

Let’s break down some key terms:

• Calorie: A unit of energy, like an inch is a unit of length. One calorie is the amount of energy needed to raise one gram of water by one degree Celsius.

• Total Daily Energy Expenditure (TDEE): The total number of calories your body burns in a day. This includes:

  • Basal Metabolic Rate (BMR): Energy used for basic bodily functions at rest.

  • NEAT (Non-Exercise Activity Thermogenesis): Calories burned through daily subconscious movement—like fidgeting.

  • TEF (Thermic Effect of Food): Energy used to digest and metabolize food.

  • Exercise: Intentional physical activity—this is actually the smallest component of TDEE.

To lose weight, you must be in a caloric deficit: burning more calories than you consume.

Approaches to Creating a Caloric Deficit

There are three general strategies to reduce caloric restriction.

1. Severe Caloric Restriction

Eating very few calories—800 to 1,000 per day—will lead to weight loss. But it’s not sustainable, can cause fatigue, increases the risk of binging, and makes it hard to exercise. This approach often leads to weight regain.

2. Exercise Alone

In theory, you could burn 800–1,000 extra calories per day through intense workouts. But in practice, most people—especially those with careers and families—don’t have the time or energy for this approach alone. In addition, this doesn’t actually work for weight loss because your body will seek to conserve calories elsewhere to keep TDEE constrained.  This has been well studied and is described very nicely in Dr. Herman Pontzer’s book Burn.

3. The Most Effective: Moderate Caloric Restriction + Exercise

This is my preferred method. I help clients moderately reduce calorie intake while including manageable workouts—usually 30-minute sessions, with a longer one on the weekend. This method promotes steady, sustainable fat loss while preserving muscle and energy. Though exercise is not a strong driving force for weight loss, those who exercise are way more likely to keep the weight off. In addition, there is nothing more powerful you can do for your health than exercise.

How I Help Clients Lose Weight: Step-by-Step

1. Start with Tracking

Even if you've lost weight before without tracking, hitting a plateau is likely. Tracking gives you the data you need to adjust.

2. Choose a Restriction Strategy

• Eat less of the same foods: For example, going from 6 eggs to 4, or eating half your usual portion of fries. This isn’t a great option if your diet is poor. Calorically-dense, processed food is not very satiating by design.  So if you simply eat less of bad food, you will constantly fight hunger and this usually leads to binge eating.

• Change the type of food: Swap calorie-dense meals for lower-calorie, more filling alternatives—like replacing a Snickers bar with oats and blueberries.

• Time-restricted eating: Also known as intermittent fasting. You will never eat the same number of calories between 10 AM and 6 PM as you would between 6 AM and 10 PM. I often recommend a 12-hour fasting window—no food between dinner and breakfast.

Eating whole unprocessed food combined with intermittent fasting can be very potent for weight loss.

3. Prevent and Manage Plateaus

Your body adapts to caloric restriction by:

• Lowering your BMR

• Reducing NEAT

• Increasing hunger signals

  
  

To counter these, I may:

• Slightly reduce calories by 50–100 per day and monitor energy level.

• If caloric intake is already very low, I might introduce a “refeed” at maintenance calories to reset the metabolism

What If You're Doing Everything Right and Still Not Losing?

Sometimes the math just doesn't add up. This is particularly common in middle-aged women or postpartum clients due to hormonal effects on metabolism.

If someone isn’t losing weight despite the plan:

• I re-calculate and further reduce intake if needed

• Ensure they’re accurately tracking

• If all else fails, I may consider medical therapy

A Word on Weight Loss Medications

GLP-1 receptor agonists like semaglutide (Ozempic) and GLP-1/GIP receptor agonists like

tirzepatide (Mounjaro) work by:

• Slowing gastric emptying

• Making you feel fuller faster and longer

They help achieve a calorie deficit without hunger. I recommend them in specific cases where traditional methods aren't working and the client is significantly struggling.

Final Thoughts

Weight loss is simple in theory, but not easy. It requires understanding your body, making

realistic adjustments, and being willing to tweak the plan as needed.

If you’re just starting out, focus on:

• Tracking intake

• Moving daily

• Eating real, whole foods

• Being patient and consistent

If you’d like help personalizing your weight loss journey, feel free to reach out at Premier

Cardiovascular Health and Performance.

Thanks for reading—and don’t forget to listen and subscribe to our PCHP podcast