Dear 100 Hour Board,
Why am I not losing weight? Is it because I am older? Two years ago if I cut the size of my meals and cut out snacks I would be able to lose about 10lbs in a month. I would gain the weight slowly but would be able to lose it again in a month. But now I am 28 and I have done the same thing (I'm even hungrier than I was a couple years ago) and my weight remains firmly in place. I know exercise doesn't help with weight loss but I would work out more frequently then. Is that the difference? Is it the types of food I eat? Why is it so hard?
-I really want to lose 10lbs
As bodies age metabolisms slow down, so that might be affecting your ability to lose weight quickly. There are also tons of other reasons your metabolism might slow down, that I went over in Board Question #87916.
We have a hormone called leptin that's basically responsible for telling our bodies when we feel full and regulating fat stores. Usually this is a good thing, as it keeps us from eating too much. However, as Wikipedia tells us,
Dieters who lose weight, particularly those with an overabundance of fat cells, experience a drop in levels of circulating leptin. This drop causes reversible decreases in thyroid activity, sympathetic tone, and energy expenditure in skeletal muscle, and increases in muscle efficiency and parasympathetic tone. The result is that a person who has lost weight below their natural body fat set-point has a lower basal metabolic rate than an individual at the same weight who is of that natural weight; these changes are leptin-mediated, homeostatic responses meant to reduce energy expenditure and promote weight regain as a result of fat cells being shrunken below normal size.
To sum that up in layman's terms, basically if someone tries to lose too much weight too fast, leptin will prevent them from losing any more weight by slowing down their metabolism. From an evolutionary point of view, this makes sense, because if your only food source suddenly disappeared and you didn't have enough food, you would want to be able to hold on to the energy from the little bit of food you did have. However, from a modern dieting point of view, this is super frustrating. In order to not see adverse effects from leptin slowing down your metabolism during your diet, most experts recommend cutting down your caloric intake by a moderate amount, and every once in a while eating a few more calories (for example, enough calories to sustain your weight, rather than to lose weight) than you normally do on your diet, to let your body know you're not starving.
Losing 10 pounds in one month is a really lofty weight loss goal. Sure, you can find all sorts of websites telling you how to do it, or even how to lose something like 20 pounds in a month (don't do that), but the general consensus among experts is that it's not sustainable, or really healthy for your body. Most experts recommend losing two to eight pounds per month. I know it's more exciting to see results sooner rather than later, but slow results are still better than no results, and they're usually more sustainable, as well. Again, if you try to lose too much weight at once, our good friend leptin will kick in and cause your body to hold on to fat stores more aggressively than it normally does.
I'm basing this on conjecture, because obviously I have no idea what you're eating, but you might want to make sure that in addition to small portion sizes, you're also not eating foods that are really calorically dense.
And finally, I'm not sure where you heard that exercise doesn't help with weight loss, but it definitely does. If someone doesn't monitor their diet at all and just exercises a lot, it probably won't get them the desired weight loss results, but that statement works in reverse as well. Dieting alone isn't nearly as effective as dieting and exercising in conjunction. In general, cardio is good for burning fat, and resistance training is good for speeding up your metabolism.