This story is part of Health by the Numbers, CNET's deep dive into how we quantify health.

The scale was viewed as the holy grail for determining how healthy you are for the longest time. With extensive research and understanding, we know that the scale doesn't take into consideration the many factors that can influence our weight. That means that weight isn't always the best indicator of health. 

What makes things more complex is when you meet someone who's the same weight, height and gender, but looks completely different than you. Weight is much more than what the scale tells you, and there are better ways to interpret your health instead of relying on a specific number. I spoke with registered dietitian and diabetes educator, Amelia Ti, to help break down the unique factors that influence weight, as well as a healthier approach we can take to understanding it. 

What determines your weight?

First, it's important to understand the many factors that influence weight. These factors include genetics, hormone levels, stress and sleep levels, moods, trauma, any medications you're taking and health conditions. 

"Our weight is more than just calories consumed versus calories burned," said Ti. She said the number on the scale is not a reliable indicator of health, since our weight is influenced by various details. In fact, many of the factors that determine our weight, such as the environment, genetics, age and gender, are beyond our control -- they were either set before we were born or are inescapable. 

The same can be said when people are dieting and aim to set a goal weight determined by the scale. "Weight is not a behavior, therefore the number on the scale cannot directly be controlled," she said. Setting a specific goal weight is not realistic or sustainable, because it implies that we can control our weight through willpower. In that same vein, Ti pointed out that dieting to lose weight or change one's body shape, size or composition, is not effective in the long-term and usually results in weight regain and cycling. There are exceptions, but we know that many diets fail.

Then there's the set point theory, which implies that we all have a natural weight that our bodies prefer to maintain. The idea is that our bodies periodically adjust our food intake (such as eating more or less) and energy expenditure to keep it balanced. Although the concept is still up for debate, studies have shown that there may be some truth to a biological control of body weight at a set point. However, weight is more complex than that, so it isn't fully proven.  

Same weight, different body composition

What about circumstances where you find yourself weighing the same as a year ago, but you notice your clothes fit a little tighter (or looser)? "Your clothes may fit differently even when your weight has stayed the same due to changes in lean body mass," said Ti. How your clothes fit can also vary on a day-to-day basis due to weight fluctuations caused by bloating or fluid retention.

Similarly, you might compare yourself to others who are the same height and weight -- yet look different from you. For example, on TikTok, women are sharing photos of themselves and labeling their exact weight to celebrate body diversity. While this may seem harmless, this trend could easily be triggering for someone with a history of disordered eating or body image issues. 

"The intentions of this TikTok trend are good, but it still places an emphasis on appearance, such as body size and shape, which may cause people to have unrealistic expectations, become overly critical, and heighten body shame and dissatisfaction," said Ti, adding, "It's important to understand that you can weigh the same as someone else, but look different because each individual has their own genetic blueprint." 

Genetics determine where exactly our bodies carry our weight. Plus, body composition also plays a major role. Body composition refers to the ratio of body fat to muscle, bones, ligaments, organs and other tissue. Again, this varies by individual and can change over time, based on many different factors.

Another aspect Ti said we should be mindful of is that we can't make assumptions about someone's physical or mental health, diet, activity or relationship with food simply by observing their appearance.

BMI and weight

Usually when the topic of weight comes up, body mass index is also discussed.

BMI is a screening tool that measures your weight and height to estimate your body fat and then categorizes you as either underweight, a healthy weight or overweight. But for individuals, BMI is not a great indicator of health. "BMI was created by a statistician based on a population of white, European males -- not a representative sample of diverse populations -- and was meant to be used as a screening tool, not a diagnostic tool," Ti said. 

Furthermore, BMI was never intended to be used to evaluate the health of an individual and does not account for gender, age, body frame or body composition. "Continued use of BMI further contributes to weight stigma in health care," warned Ti, adding that even though the health care system probably won't move away from the concept, we can avoid relying on BMI as the sole indicator of our health because it doesn't tell the whole story. 

When weight matters

It would be remiss to say that weight never matters. There are certain circumstances when it's important to monitor your weight. For example, observing your weight during pregnancy is necessary to make sure you gain the right amount of weight for a healthy gestation.

Weight can also matter if you have a known heart condition. Ti said those with congestive heart failure have to monitor their weight closely because fluid build up in the body causes weight fluctuations and changes that occur as a result of the disease itself.

Additionally, you should be aware of your weight if you have a health condition, such as diabetes, that requires a specific medication dosage. Your doctor will determine your dosage based on your weight to make sure you're being prescribed the right amount.

If you have a clean bill of health, Ti suggested you place less emphasis on having a specific weight. "Ultimately, the focus should be improving your health through changes in your behaviors, habits, thoughts, and how you feel throughout the day," she said. Improvements in mood, sleep, energy and strength will make a bigger difference than what the scale tells you in the morning. 

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.