What’s the Best Diet: The Science of Weight Loss

Dieting with Donuts?

What’s in a Diet?

Diet is arguably, the biggest component of a healthy lifestyle.  It is no wonder people scour the internet looking for the latest and best dieting trends.  Buzzy words like “keto”, “paleo”, and “IIFYM” get tossed around.  People will fiercely defend their diet of choice with their own anecdotal “evidence”.  But how can the average person really know what diet is the best for them?

Dieting 101

Breakfast Idea
Balanced breakfast with all three macros and nearly the entire day’s recommended daily intake of vitamin C and vitamin A.

Basically, all diets vary in three macronutrients.  “Macros” is a term that refers to carbohydrates, fats, and proteins.  Some diets stress the importance of eating whole foods, no processed foods, while others allow you to choose between processed foods as needed for convenience.

There is significant variability in the way we process macros and micronutrients (vitamins and minerals).  In clinic, we’ve seen people lose weight on keto, paleo, low-fat, and low-carb diets.  Ketogenic or extremely low-carb diets are extremely popular at the moment.  However, there is one major criticism of the keto diet.  In studies where calories are strictly managed by the researchers and not simply reported by patient journals, most of those studies find little to no benefit of being ketogenic.  Evidence also shows differing ability to achieve and maintain a state of ketosis, on an individual basis.

Low-Carb vs Low-Fat

A new study: “The Effect of Low-Fat versus Low-Carbohydrate Diet on 12 Month Weight Loss in Overweight Adults and the Association with the Genotype Pattern and Insulin Secretion” was published in the Journal of the American Medical Association on February 20, 2018.  This study included over 600 non-diabetic adults  with BMI between 28-40.  Patients were evaluated based on their genetic predisposition to weight gain, as well as their innate insulin secretion patterns 30 minutes after a glucose challenge.  This means they were able to classify how a patient’s body responded to carbohydrate intake.  Then they looked at whether people who did not ideally process carbohydrates could actually lose weight on low-fat diets.

There Was No Difference Between Low-Carb and Low-Fat Groups

The macronutrient distribution for the healthy, low-fat diet was 48% carbs, 29% fat, and 21% protein.  The healthy, low-carb diet was 30% carbs, 45% fat, and 23% protein.  The low fat group had an average weight loss of 5.3kg, while the low-carb group had an average of 6kg weight loss. Genetic markers showed that 40% of the study participants had a low-fat genotype.  30%  of participants had a low-carbohydrate genotype.  Despite these genotypes, there was no difference in patients who had genotypes predisposing them to carb or fat intake sensitivity.  They didn’t see any interaction between their insulin secretion ability and weight loss between the two groups.

Calorie is King

Macros
3/4C of Cinnamon Toast Crunch or 187g of Blueberries? They both have the same amount of carbs/calories, but one is more likely to keep you full and has more vitamins.

Regardless of what diet you choose, the key to losing weight is burning more calories than you consume.  Focus on whole foods and home-cooked meals with plenty of lean meat, healthy fats, and veggies is ideal for overall health.  However, when it comes to shedding lbs, your body only cares how many calories go in and how many go out. The study showed no significant interaction between a patient’s genetics and their ability to lose weight based on different dietary plans. Diets that swear you can eat as many eggs or slices of bacon you want in a day and lose weight, as long as you don’t eat those evil carbs, are leading you astray.

Consistency and Sustainability

1 out of 5 patients didn’t make it through the entire study over the course of the year they collected research.  Results do show that you are more likely to lose weight if you stick with a diet for a year.  There are diets claiming to get results in 2 weeks with a juice cleanse.  Or some try to fix your sugar “addiction” in 21 days.  They are all setting you up for failure.  These rigid diet schemes are difficult to maintain long-term in real life.

Consistency
Consistency is key. From unmeasured 80/20 Paleo to two years of maintaining a 58kg weight class with counting macros and incorporating foods I love rather than binging.

The most effective diet is one you can avoid derailing from after only a month or two.  It is also important to know that chronic calorie deficits can have adverse effects.  It’s best to only operate on a caloric deficit for 8-12 weeks at a time before giving your body a break.  That doesn’t mean 8-12 weeks of extreme dieting to then binge for the next 4 weeks before you hop back on the wagon.  Add the 300-500 calories back into your diet with the foods you’re already eating and maintain your new weight for a month or two.

What’s the best diet?

Go ahead.  Pinterest those Keto recipes.  Or do your macro math to figure out how to work in that pizza night with the family.  The diet that fits your lifestyle and allows you to be compliant in the long-term will ultimately give you the best results!

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