Weighing diet strategies

Both low-fat and low-carb diets can be effective for fat loss, but consistency and counting calories are key


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Are carbs to blame? That’s what a few readers think who responded to my column The Naked Truth from two weeks ago. I talked about my entire game plan to drop body fat before summer (hint: it doesn’t involve cutting carbs to zero!) and the importance of figuring out calories.

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Are carbs to blame? That’s what a few readers think who responded to my column The Naked Truth from two weeks ago. I talked about my entire game plan to drop body fat before summer (hint: it doesn’t involve cutting carbs to zero!) and the importance of figuring out calories.

What these readers are referencing is the carb insulin model (CIM) of obesity, originally proposed by Dr. David Ludwig and popularized by the likes of Gary Taubes and Jason Fung.

The CIM basically states that people don’t get obese from eating too many calories, they get obese from chronically elevated insulin (from carbohydrate intake) which traps fat in fat cells, making it inaccessible to the rest of the body to be used as energy.

Calories 101

Before we get to the data comparing diets, let’s discuss some basics. Calories are a measurement of the amount of energy within a food. The 3,500-calorie rule is generally understood to equal one pound of body weight change.

In layman’s terms, if an individual has a goal of losing one pound per week, they will have to reduce calorie intake by 500 calories per day (500 x 7 = 3,500) to achieve one pound of weight loss. But one pound per week can look very different depending on how it’s achieved. The individual who strength-trains and eats sufficient protein while reducing calories largely will lose fat while someone cutting calories and nothing else may lose a good percentage of muscle.

What the research shows

How does the CIM stack up against conventional calorie restriction? As with anything, you can generally find something to support your bias and that’s no different here.

We have a mountain of research studies that compare low-fat to low-carb strategies, when the two most important variables, calories and protein, are accounted for. In a 2017 meta analysis, researchers found no net benefit to low-carb diets, and perhaps a slight advantage to the opposite, high-carb, low-fat diets.

A 2021 Ludwig study leaned in favour of low-carb diets on the basis of higher daily energy expenditure. Ludwig’s lab found more calories burned in low-carb dieters, but it didn’t lead to more losses of body fat. In response, other researchers called into question the methods used to measure energy expenditure, as without fat losses to show for it, can we really take much from this finding?

Ozempic throws CIM under the bus

Even more damaging for the CIM model is the new class of GLP-1 mimetic drugs (including Ozempic) that increase insulin but lead to considerable weight loss. If controlling insulin was the most important variable, as the CIM model contends, how could you take a drug that elevates insulin and lose body fat?

These are powerful appetite suppressants that show people averaging 15 per cent loss of body weight in year-long studies, with no increase in metabolic rate. The “magic” is in reducing appetite so one eats less calories.

What should you do?

Much is made of the low-carb vs. low-fat debate, but based on the evidence we have today, it does not seem to make a difference.

Both low-fat and low-carb diets (and everything in between) appear to be equally effective for fat loss so long as protein and calories are equated between diets.

Low-fat diets work by reducing fat so you eat fewer calories by default. Low-carb diets work by reducing carbohydrates so you eat fewer calories by default. Intermittent fasting works by restricting your eating to one eight-hour period each day so you eat less calories by default. You get where I’m going with this. It all comes down to energy balance: if you’re gaining weight, you’re eating more calories than you’re expending and vice versa if you’re losing.

The best diet is one you can stick to. If you enjoy a ketogenic diet and can sustain it for a long time, go for it. I personally prefer focusing on the fundamentals. Case in point, we just awarded our “Client of the Quarter” vacation giveaway to Sean, who lost 108 pounds in a year.

Last year he noticed he was getting winded going up flights of stairs and didn’t have the energy to keep up with his hectic work and travel demands — nor to be at his best for his family!

Sean had read my Free Press column and the simple message resonated. Despite a healthy dose of skepticism, he took the leap.

Physical changes aside, his health markers one year on are the most positive developments:

● Body mass index BMI dropped 15 points

● Blood pressure dropped from 160/90 to 120/60

● Resting heart rate fell from 80 beats per minute to 60

● Over 30 inches in circumference off his midsection (not a misprint)

So, how did Sean do it? The process to make this happen is simple on paper.

Start with the big 5 basics

1. Walk 8,000-10,000 steps daily by tracking your movement with wearable technology (even your smartphone does this by default!).

2. Drink two to four litres of water daily and track your intake with a calibrated jug or water system.

3. Eat mostly whole foods with 80 per cent of your meals prepared at home, not purchased at a restaurant or drive-thru. You’ll probably need to track your calories and proteins if eating healthy has gotten you nowhere in the past.

4. Strength-train at least three times a week for 30 minutes. The role exercise plays is primarily in maintaining muscle here, so choose wisely. It’s not high-intensity interval training (HIIT), boot camps or circuit workouts that serve this role best.

5. Get seven-plus hours of sleep most nights by committing to a set bedtime.

If you were able to implement these five habits at 80 per cent consistency, I’m confident that in three months…

● You could be down 20 pounds — or more — when you step on the scale;

● You could be stronger and more toned than you’ve ever been;

● You could be eating carbs — every single day! — and making your keto friends jealous;

● You could feel like you’re not working out that hard and still seeing better results than with those boot camps.

But navigating life’s challenges, staying consistent and customizing it to yourself is the tricky part. If you’re willing to do the legwork, you’ll understand what matters and have all the tools to keep the weight off.

Mitch Calvert is a Winnipeg-based fitness coach who has helped more than 1,500 people transform their lives over the past decade. Visit mitchcalvert.com to grab a free copy of his metabolism jumpstart or drop him a message at mitch@mitchcalvert.com.

Mitch Calvert

Mitch Calvert
Fitness columnist

Mitch Calvert is a Winnipeg-based fitness coach for men and women like his former self. Obese in his 20s, he lost 60 pounds himself and now helps clients find their spark and lose the weight for life.

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