Many people who start working out often think that as long as they are exercising, they can eat whatever they want. However, on the flip side, many people believe that controlling one’s diet is more important. So, which one is true? What does more weight do in your fitness journey? A recent study published in the Proceedings of the National Academy of Sciences supports this idea, finding that diet, not a lack of physical activity, is the main reason for the obesity epidemic. This doesn't mean exercise isn't important—it absolutely is—but if your main goal is weight loss, the study suggests that what you eat matters more than how much you work out. Obesity on the other hand is another factor that prompts more research like this. In recent years we have seen obesity rates increase, current stats showing that one out of eight people are obese (World Health Organization). The statistics show that adult obesity rates have quadrupled since 1990. Is diet the cause of this? Diet vs. Exercise: Which Matters More for Weight? To understand whether consuming too many calories or not burning enough calories is the primary cause of obesity, a team of researchers compared data from over 4,000 people across six continents. The groups included highly active people like farmers and hunter-gatherers, as well as people from industrialized countries who were much less active. The study found that people in industrialized nations had higher body weight and body fat. However, after adjusting for body size, the researchers found that they were only burning a little bit fewer calories each day than the more active groups. This was a surprising discovery, considering their lifestyles were far less active. This suggests that the rise in obesity isn't due to people failing to burn enough calories, but rather because they are simply eating too many calories. Does A Diet-First Approach Work For Weight Loss? While this study is observational and can't prove a direct cause-and-effect relationship, other experts agree with its findings. According to one expert, decades of research have shown that physical activity makes only a "minor contribution" to weight management. A few studies have suggested the opposite, and some researchers argue that a combination of diet and exercise is best for long-term weight loss. However, most of the evidence supports focusing on diet first. One likely reason is that our bodies naturally adapt to exercise. When you become very active, your body becomes more efficient, so you don't keep burning more and more calories over time. Does Exercise Not Matter For Weight Loss? This research does not mean you should stop exercising. In fact, experts call exercise "the most powerful life-extending intervention we have," with clear benefits for both physical and mental health. However, when it comes to weight, the message is clear: focus on the number of calories you're eating, not just the number you're burning. Experts recommend a diet rich in fresh fruits, vegetables, whole grains, and lean proteins while cutting back on processed foods. The study also points out that the responsibility for these changes isn't just on individuals. It's often easier and cheaper to buy junk food than healthy food. Governments and public health officials have a role to play in making healthy, fresh foods more accessible and affordable for everyone.