Revealed: The Most Common Weight-Loss Mistakes That Nearly Every Dieter Makes

According to the Centers for Disease Control (CDC), approximately 43% of adults are overweight, of which 40% are classed as obese (1). In short, being overweight is the new norm, and a lot of people are suffering the ill effects of being overweight.

These include:

• Cancer
• Cardiovascular Disease
• Gastrointestinal Disorders
• Kidney Disease
• Liver Disease
• Mental Health Issues
• Osteoarthritis
• Respiratory Problems
• Sleep Apnea
• Type 2 Diabetes

While some people are content to be overweight, others are desperate to shift those unwanted pounds.

Based on information from the CDC, about 50% of overweight people try to lose weight Unfortunately, a whopping 89% of them are unsuccessful, and many of those who do manage to lose weight regain what they’ve lost in 12 months or less (2).

I’m a veteran personal trainer and I specialize in helping people lose weight and keep it off. Needless to say, my results are much better than the figures provided by the CDC; I’d soon be out of a job if my success rate was a measly 11%!

In this article, I reveal the most common mistakes people make when trying to lose weight. Avoid these pitfalls and you’ll soon be on your way to achieving your weight loss goals.

The Most Common Diet Mistakes You MUST Avoid

A lot of my clients come to me for weight loss or weight advice. Most have tried to lose weight in the past but have been unsuccessful. They’ve either failed to reach their target weight or regained the weight they worked so hard to lose.

In many cases, the reasons for their failure are abundantly clear – to me, at least: they’ve made one or several of the most common weight loss mistakes.

If you’ve struggled in the past to lose weight or keep it off, you’ve probably made some of these mistakes, too. In this section, I reveal the most common dietary missteps and what you need to do instead.

1. Trying to Lose Weight Too Fast

I’m often asked what the best way is to lose weight, and usually, my slightly tongue-in-cheek answer is, “Slowly!”

Needless to say, the person asking the question was hoping for a more specific answer regarding diet or exercise, but going slow is arguably the cornerstone of any successful weight loss journey.

While rapid weight loss (more than two pounds per week) is possible, it requires a very strict diet and a lot of exercise. Such an extreme approach is impractical and unsustainable for most people.

After all, it’s estimated that one pound of fat is equal to 3,500 kilocalories so to lose a lot of weight quickly, you’ll need to reduce your food intake or increase your exercise levels to shave more than 7,000 kilocalories off your energy balance per week. Such a deficit will leave you hungry, tired, and possibly malnourished.

Related: How Much Calorie Deficit is Too Much? Find Your Safe Limit

So, while it may be tempting to try and lose weight as fast as possible, your chances of success are much higher if you take it slow and easy. It’s better to lose a pound a week for a year than try to lose 20 pounds in a month and then quit.

2. Following an Unsustainable Diet

There are hundreds of diets, all of which proclaim they are the best way to lose weight. Many promise rapid weight loss, while others say you can lose weight simply by eating certain “magical” foods.

Unfortunately, most of these diets fail to deliver on their promises.

Ultimately, any diet can help you lose weight provided it:

• Creates an energy deficit of around 500 kcal a day
• You can stick to it for as long as it takes to reach your goal weight

In my experience, the more extreme a diet is, the harder it is to maintain. That’s why I encourage my clients to create their own weight loss eating plans built around these proven principles.

That said, if you are looking for a healthy, balanced, enjoyable diet, I recommend you take a look at the Mediterranean diet, which is often described as the world’s healthiest eating plan.

3. Not Eating Enough Protein and Fiber

Most diets limit or eliminate certain foods or food groups to lower your kilocalorie intake. For example, you might eat less carbohydrates, sugar, or fat. However, while what you don’t is important, what you do eat is probably more so.

Getting enough protein is critical for successful weight loss. Protein, which we get from things like meat, poultry, fish, nuts, seeds, and beans, offers several benefits to dieters, including:

• Elevated metabolism for faster weight loss
• Increased satiety for less hunger
• Muscle preservation to prevent metabolic slow-down
• More stable blood glucose for sustained energy

In contrast, fiber contains no kilocalories but is vital for your digestive health, promotes satiety, helps stabilize your blood glucose, and bulks up your meals without making them more calorific. Good sources of fiber include whole grains, vegetables, and fruit. You can determine your fiber needs with this calculator.

4. Drinking Your Kilocalories

The average 12 oz. can of soda contains around 150 kilocalories, all of which come from sugar. That’s about ten teaspoons or 40 grams. Many energy drinks, fruit juices, and smoothies contain even more, as do some sweetened tea and coffee-based drinks. And, of course, bigger servings, e.g., Big Gulps, contain more still.

Consequently, even a couple of regular-sized sodas have the potential to wipe out your kilocalorie deficit for the day so that, rather than lose weight, you actually continue gaining.

To avoid this problem, I tell my clients to avoid drinking their kilocalories. Liquid kilocalories don’t fill you up like food does, and it’s easy to consume a lot of sugar, derailing your weight loss efforts.

Instead, you should slake your thirst with sugar-free drinks like diet soda, water, and unsweetened tea and coffee. Even fruit juice is best avoided as it contains more kilocalories than a piece or two of fruit while being stripped of fiber, vitamins, and minerals.

5. Having Too Many Cheat Meals

Cheat meals are one of the most appealing aspects of many diets. The freedom to eat the foods that are banned the rest of the time can make an otherwise boring diet much more palatable.

Unfortunately, cheat meals can also derail your progress.

For example, let’s say you’ve cut your food intake by 500 kilocalories a day, creating a weekly 3,500 kilocalorie deficit. All being well, this should result in a one-pound weight loss.

To celebrate, you chow down on a cheat meal of pizza, ice cream, and beer. This one feast will probably contain more than 3,500 kilocalories, completely wiping out your week of clean eating.

So, while you may feel like you deserve a cheat meal, you mustn’t turn it into a binge.

Unfortunately, most weight loss diets are so strict and unpleasant that cheat meals are the only way to make them tolerable. That’s why less extreme, more sustainable diets are better. While your weight loss progress will be slower, you’ll be less inclined to break your diet every few days.

Related: 7 Ways to Stop Cheat Meals Ruining Your Diet

6. Not Tracking Your Food Intake

There is a saying in business that has also been adopted in fitness, “You cannot manage what you do not measure.” In other words, how can you adjust your diet or workout program if you don’t actually know how much you are eating or how often/hard/long you are exercising?

Losing weight requires a kilocalorie deficit and the only way to create such a deficit is to a) know how many kilocalories you need to maintain your current weight, and b) how many kilocalories you are eating.

Not having this information means you’ll always be firing blind.

Consequently, regardless of which diet you follow, you must weigh and measure your meals so you can estimate your kilocalorie intake. Then, based on your progress, you can increase or decrease your food intake to achieve the results you want.

Yes, weighing and measuring your food is a bit of a nuisance and can be time-consuming at first. However, using an app makes the entire process much easier, and you’ll soon find that you eat many of the same meals over and over, so you only need to weigh and measure them once.

7. Eating Too Many “Diet” Foods

Many of the foods that caused you to gain weight in the first place, e.g., cookies, candy, ice cream, soda, etc., are now available as “diet foods.” The manufacturers often suggest that you can replace your usual treats with these diet-friendly alternatives to lose weight without giving up your favorite foods.

Sadly, this is nothing by marketing hyperbole.

Diet cookies, candy, etc. are only marginally lower in kilocalories, and the saving is not enough to result in weight loss. Also, eating these foods can create a phenomenon called the “health halo,” where you’re tempted to eat more of a diet food than the original version because it’s promoted as being healthier or better for weight loss.

For example, instead of eating two standard cookies that contain 100 kilocalories each, you might eat four diet cookies that contain 75 kilocalories. Needless to say, you’ve not saved any kilocalories and, instead, have increased your intake by 50%.

Closing Thoughts

Losing weight and keeping it off should be a relatively straightforward process as it’s mostly a question of balance. Eat less, move more, and create the energy deficit that forces your body to burn fat for fuel.

It really is that simple!

Unfortunately, a lot of people make weight loss far harder than it needs to be by spreading misinformation and promoting diets and products that are ineffectual and can even be dangerous.

So, don’t get suckered into following another fad diet or extreme workout plan. Instead, make sure you eat healthily, create a small, sustainable energy deficit, try to be active most days of the week, and avoid the mistakes that I’ve listed in this article.

While your progress might be slower than you’d like, any progress is better than failing to lose weight or regaining the weight you’ve lost.

Questions? Comments? Drop me a line below and I’ll get back to you ASAP!

References:

1. Centers for Disease Control and Prevention. (2024, September 12). *New CDC data show that adult obesity rates exceed 35% in 23 states*. Retrieved January 8, 2025, from https://www.cdc.gov/media/releases/2024/p0912-adult-obesity.html
2. Martin, C. B., Herrick, K. A., Sarafrazi, N., & Ogden, C. L. (2018). *Attempts to lose weight among adults in the United States, 2013–2016*. NCHS Data Brief, no. 313. Hyattsville, MD: National Center for Health Statistics. Retrieved January 8, 2025, from https://www.cdc.gov/nchs/products/databriefs/db313.htm

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