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Why So Many People Mistake Soreness for Progress
One of the most common things I hear from clients after a workout is, “That was a great session. I’m so sore.” I understand why people say it. Soreness feels like proof that something productive happened. It feels like evidence that the workout was intense enough to “count.” But when the goal is fat loss, that mindset can be misleading.
A hard workout is not automatically a better fat-loss workout. In fact, if a session leaves you so sore that you move less, sleep worse, or train less effectively later in the week, it may actually work against your fat-loss efforts. A recent resistance-training study provides a great example of this point. (1)
The big practical question is simple: does a workout need to leave you very sore to help with fat loss? Based on this study, the answer is no. The evidence suggests that more soreness did not produce better fat loss. (1) What matters more is using a training approach that you can recover from well enough to keep moving, sleeping, and training consistently.
What the Study Compared
In the 2024 study by Carneiro and colleagues, researchers compared two resistance-training routines in 23 well-trained men over 8 weeks. (1) One group used a full-body routine, training all major muscle groups across the week. The other used a split-body routine, training muscle groups on separate days. Importantly, the weekly set volume was matched, so the comparison was not simply “more work versus less work.” (1)
What the Study Found
What happened was striking. The full-body group lost fat, while the split-body group slightly gained fat on average. (1) The full-body group also showed more favorable changes in regional fat loss, including the upper limbs, lower limbs, and gynoid region. (1) At the same time, the split-body group experienced substantially higher delayed onset muscle soreness, especially in the legs. (1)
Outcome after 8 weeks | Full-body routine | Split-body routine |
|---|---|---|
Whole-body fat mass | -0.775 kg | +0.317 kg |
Upper-limb fat mass | -0.085 kg | +0.066 kg |
Lower-limb fat mass | -0.197 kg | +0.055 kg |
Gynoid fat mass | -0.142 kg | +0.123 kg |
Lean mass change | +0.8 kg | +0.5 kg |
That last point matters. Both groups appeared to gain lean mass, and neither routine was clearly superior for lean-mass gains.1 In other words, the full-body group did not have to sacrifice muscle gain to get the better fat-loss result. From a coaching standpoint, that is a very useful reminder that a program does not need to feel maximally punishing to be productive.
Why More Soreness Can Backfire
The study also points us toward an important mechanism: soreness may change what you do outside the gym. The authors found that higher soreness tracked with worse fat-loss outcomes more clearly than training volume itself. (1) They did not directly measure free-living physical activity, so we should be careful not to overclaim, but their interpretation is very plausible. If your legs are wrecked after training, you may not notice that you are walking less, standing less, moving less, and generally conserving energy for the rest of the day. That subtle drop in daily movement can matter a lot for fat loss. (1)
Severe soreness may also reduce strength and performance. DOMS is associated with reduced muscle strength, impaired performance, pain, swelling, and decreased muscle function. (2) If movement feels uncomfortable, people may naturally do less outside the gym, which can reduce daily energy expenditure. (1) Lingering soreness can also make it harder to train with the effort, range of motion, or consistency you want later in the week. (1 2)
This is one reason I often tell clients that fat loss is not won during the hardest 45 minutes of your day. It is won by what your training allows you to sustain across the other 23 hours. A workout that is challenging but recoverable may support more total movement, better adherence, and better training quality across the week than a workout that leaves you limping for three days.
The Sleep and Appetite Connection
There is another layer here that the study did not test directly, but that is worth considering in real-world coaching: sleep. Poor sleep can make fat loss harder by shifting hunger, food reward, and caloric intake in the wrong direction. Experimental sleep-restriction research has shown that people tend to eat more calories when sleep is restricted, even when energy expenditure does not meaningfully increase. (3 4) So if brutally hard training leaves you restless, uncomfortable, or sleeping poorly, that could create another pathway by which “harder” backfires.
In practical terms, short sleep has been associated with higher caloric intake. (3) Controlled research has also found that sleep restriction can increase calorie intake without a matching increase in energy expenditure. (3 4) That means if training soreness disrupts sleep, appetite regulation and food choices may become harder to manage, even if the workout itself burned calories.
Consistency Beats Punishment
I also think this helps explain another pattern clients experience all the time. When a workout leaves you debilitatingly sore, you are more likely to skip the next session, shorten it, sandbag it, or avoid the exercises that hurt. Even if you still show up, the quality of your training may drop because your body is still trying to recover. Again, the message is not that training should be easy. The message is that training should be appropriately challenging and compatible with the rest of the habits that support fat loss.
This is why I would frame the lesson from this study as follows: the best workout for fat loss is not the one that hurts the most; it is the one that improves body composition while preserving your ability to move, recover, sleep, and stay consistent. Full-body training happened to outperform split-body training in this specific study of well-trained men, but the bigger principle is broader than any single split. The precise workout style matters less than whether the plan fits your recovery capacity and supports the lifestyle behaviors that drive fat loss over time.
That does not mean soreness is always bad. Some soreness is normal, especially when you begin training, return after time away, or introduce a new movement. But soreness should be viewed as a possible side effect, not as proof that a workout was effective. If soreness is so severe that it changes how you move, how you sleep, how much you eat, or whether you train later in the week, it may be too costly for your current goal.
A better set of questions to ask after a workout would be: can I recover from this and still move well tomorrow? Can I repeat this consistently for the next 8 to 12 weeks? Does this support my sleep, appetite control, and routine? Those are far more useful questions than asking how sore the workout made you or whether it felt punishing enough to count.
Final Takeaway
So if your goal is fat loss, do not chase soreness for its own sake. Chase a training plan that you can execute consistently, recover from properly, and pair with high-quality habits outside the gym. The workout that looks hardest on paper is not always the one that gets the best result. Sometimes the smartest program is the one that leaves you feeling worked, not wrecked.