5 Ways to Tell If You’re Losing Weight Healthily or Unhealthily

According to the World Health Organization (WHO), 43% of American adults are overweight while 16% are obese. More worryingly, one in six children under the age of five are deemed overweight. The WHO also reports that worldwide, 2.5 billion adults are overweight, including 890 million who are living with obesity (1).

Being overweight is a leading cause of many diseases and can have a big impact on the quality and length of your life. The health risks of being overweight include (2):

• Heart disease
• Type 2 diabetes
• High blood pressure
• Stroke
• Certain types of cancer (e.g., breast, colon, and endometrial cancer)
• Osteoarthritis
• Immobility
• Sleep apnea
• Fatty liver disease
• Kidney disease
• Pregnancy complications

Of course, not everyone is aware of or even cares about the health implications of being overweight. Instead, they just want to shed their excess pounds to look leaner and more toned.

It’s hardly surprising then that, as a veteran personal trainer, a significant proportion of my clientele come to me for weight loss advice. In most cases, they’ve tried to lose weight before but failed. That’s because many popular diets are unsustainable and ineffective, and some are actually unhealthy.

But how can you tell if you are losing weight healthily, or if your latest diet is harming your health?

In this article, I reveal five ways to tell if you are losing weight healthily or unhealthily.

Five Signs of Healthy vs. Unhealthy Weight Loss

Losing weight should do you nothing but good, improving your appearance AND health simultaneously. However, in my experience, this is not always the case, and some people hurt their health even as they shed those unwanted pounds.

But how can you tell the difference between healthy vs. unhealthy weight loss? Here are five tell-tale signs plus a host of tips that will help you lose weight without harming your health!

1. You Are Losing Weight Too Quickly

Most overweight people have been that way for a while. After all, it often takes years of overeating and sedentarism to gain weight. Of course, there are exceptions, like eating too much and exercising too little over the holidays. However, most people are what can best be described as chronically overweight.

And yet, despite this, almost everyone wants to lose their extra body weight in just a few weeks. Consequently, workouts and diets that promise rapid results are all the rage.

Unfortunately, losing weight quickly is seldom sustainable and can even be unhealthy (3).

While this is something of an oversimplification, it’s generally accepted that one pound of stored body fat equals about 3,500 kilocalories. So, to lose one pound, you need to burn 3,500 kilocalories more than you consume or lower your food intake by the same amount. This is called an energy deficit.

Related: Energy Deficit Calculator

For most people, a sustainable, healthy energy deficit is 500 kilocalories per day, which should result in one pound of weight loss per week (7 x 500 = 3,500 kilocalories/one pound). Some people can lose more, e.g., two pounds per week, but that’s generally considered the upper limit for healthy weight loss.

Losing more than 1-2 pounds a week is commonly associated with numerous risks, including:

• Malnutrition
• Severe hunger
• Low energy
• Mood swings
• Muscle atrophy
• Heart problems
• Kidney problems
• Weakened immune system
• Hypotension (low blood pressure)
• Digestive problems
• Brittle nails and bones
• Hair loss
• Skin problems

Despite this, some people still try to lose weight too fast, usually with extreme diet and exhaustive workouts. While you may be able to stick to such an aggressive plan for a few days or even a week or two, failure is almost inevitable, and the risks of such lose-weight-fast programs almost always outweigh the benefits.

While losing 1-2 pounds per week may seem insignificant, stay on track for a few months and those pounds really start to add up. In addition, you’ll also find it easier to keep the weight off once you reach your body weight goal.

2. You Are Getting Weaker Instead of Stronger

Your body is the ultimate survivor. It’s hardwired to adapt so you can thrive in any number of adverse situations. This is why you shiver when you are cold, sweat when you are hot, and get fitter when you exercise; these are all mechanisms designed to keep you alive.

Faced with prolonged hunger, your body does its best to make your fat stores last as long as possible. It does this by lowering your metabolic rate and using muscle tissue for fuel. Consequently, humans are equipped to survive lengthy famines, which helps explain why we didn’t die out the first time that food supplies ran short.

However, your body cannot tell the difference between involuntary starvation, e.g., due to a failed crop, and your latest diet. It responds the same way to both “threats.”

Of course, even extreme diets cause weight loss, so you hop on the scales and marvel at the five pounds you lost in a week. Unfortunately, rather than losing fat, you end up losing muscle, and that’s a problem.

Less muscle means less metabolically active tissue. This lowers your basal metabolic rate, which is the amount of energy your body uses in a day. A lower metabolic rate will ultimately undermine future weight loss and also means you are more likely to regain lost weight when you start eating normally again.

Losing muscle can also hurt how you look, leading to a phenomenon called “skinny fat.”

But, how do you know if you are losing fat or muscle? After all, your scales won’t tell you the difference.  

While you could use skin calipers, a bioelectrical impedance machine, or get an MRI to measure your body composition, a more accessible indicator is your performance in the gym.

Losing muscle is almost always accompanied by a reduction in strength. So, if your reps are dropping or you have to reduce your training weights, you are probably losing more muscle than fat.

3. You Are Developing a Poor Relationship with Food

A little hunger and feelings of food deprivation are normal during most diets. After all, you’ll be eating less, and some of your favorite foods will probably be off the menu. Cravings are also a normal response to a diet. However, these should all be quite manageable, and you should be able to overcome them by flexing your willpower.

Coincidently, this is why so many diets include so-called cheat meals. They provide a short mental and physical break from your diet, acting as a reward for sticking to the plan the rest of the time.

Related: 7 Ways to Stop Cheat Meals Ruining Your Diet

All that said, very strict diets or diets based on unsound nutritional practices can create an unhealthy relationship with food, possibly leading to disordered eating. The signs that your diet may be harming your mental health include:

• Binging
• A preoccupation with food
• Obsessive food weighing/measuring
• Feelings of severe guilt if you break your diet
• Developing rituals associated with food
• Misuse of laxatives
• Misuse of weight loss supplements or drugs
• Purging/vomiting
• Avoiding social situations involving food
• Exercising excessively to compensate for eating
• Feeling anxious, stressed, or guilty about eating
• Distracted by constant thoughts of food

Needless to say, all of these responses are extremely unhealthy and any diet that makes you feel this way should be avoided.

Related: Fix Your Diet Forever in Six Weeks

4. You Keep Getting Sick

Your diet should be more than just a way to control your weight. It should also provide you with all the nutrients your body needs to function correctly. This includes adequate protein, fiber, vitamins, minerals, and other essential substances you need to stay healthy.

A well-functioning body is generally a healthy body, ready and able to fight off illness, infection, germs, and anything else that could cause you harm.

However, some more radical diets, such as keto, carnivore, and paleo reduce your intake of certain essential nutrients. Consequently, they could undermine your immune system, or otherwise harm your health.

Signs that your diet may be making you sick include:

• Frequent colds
• Food allergies
• Nausea
• Constipation
• Diarrhea
• Stomach distension/bloating
• Skin eruptions
• Dizziness
• Lethargy
• Changes in blood pressure
• Changes in blood lipid profile

These symptoms suggest that your diet is hurting your health, even as you lose weight. Needless to say, this is NOT what a good diet should do!

5. Your Energy Levels Are Lower Than Normal

Losing weight invariably means consuming less food and fewer kilocalories than usual. After all, this is what forces your body to burn stored fat. However, your body is quite happy using fat for fuel, and most people have plenty to lose, so there should be an abundance of energy.

Despite this, a lot of people report feeling tired and lethargic during a diet. They may even lack the energy to exercise, or their job performance may suffer. This should not be the case and strongly suggests that the diet is doing more harm than good.

In most cases, severe fatigue – physical or mental – is the result of following a diet that’s too restrictive, too low in carbohydrates, contains too few calories, or is otherwise lacking in essential nutrients. Such a diet may also affect your ability to sleep, making matters even worse.

Healthy people have all the energy they need to power through their day. While it’s normal to feel tired after strenuous mental or physical activity, you should have no problem recovering and soon be ready to do it all again.

If you feel drained, lethargic, mentally foggy, weak, or otherwise lacking in energy, it’s a good indicator that your diet is not providing the energy and nutrients you need to function at your best. Worse still, your diet could be undermining your short and even long-term health.

Closing Thoughts

Going on a diet should not make you miserable, tired, or unhealthy. On the contrary, while losing weight will undoubtedly require some willpower and self-control, the process should be relatively straightforward, painless, and health-enhancing.

The best way to lose weight and keep it off is to avoid diets that promise rapid results. Invariably, it’s these extreme eating plans that give dieting for weight loss a bad name.

So, plan on losing 1-2 pounds a week, and taking as long as necessary to reach your weight loss target. While this slow progress isn’t going to set the internet alight, it is the best way to lose weight and keep it off.

Finally, keep an eye out for the five signs of unhealthy weight loss discussed in this article. Change your eating plan if you experience any of them, as their presence suggests that your diet is causing more harm than good.

Questions or comments? Please drop me a line below and I’ll get back to you ASAP!

References:

1. World Health Organization (2024): Obesity and Overweight. Retrieved from https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
2. Field, A. E., Coakley, E. H., Must, A., Spadano, J. L., Laird, N., Dietz, W. H., Rimm, E. B., & Colditz, G. A. (2001). Impact of Overweight on the Risk of Developing Common Chronic Diseases During a 10-Year Period. JAMA Internal Medicine, 161(13), 1581-1586. doi:10.1001/archinte.161.13.1581
3. Ashtary-Larky D, Bagheri R, Abbasnezhad A, Tinsley GM, Alipour M, Wong A. Effects of gradual weight loss v. rapid weight loss on body composition and RMR: a systematic review and meta-analysis. Br J Nutr. 2020 Dec 14;124(11):1121-1132. doi: 10.1017/S000711452000224X. Epub 2020 Jun 24. PMID: 32576318.

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