A lot of people have mixed things to say about detoxes and cleanses, and a lot of that information is incorrect, misrepresented, or wrong. There are a lot of people out there who are more than happy to lie to your face if it gets them a sale, and you'll be left suffering, none the wiser. Detoxes are one of the areas where a lot of people are exploited, and we're generally trying to help set the record straight.
One thing that is generally true is that some people can feel hungry when they're detoxing.
This can happen for a few different reasons, so let's discuss those reasons.
Detoxes Restrict Calories
One of the main reasons detoxes make you feel hungrier than usual is because, well, you are hungrier than usual. A lot of detoxes and cleanses involved restricting your diet to near-nothing, limiting you to a few supplements and some juice or a smoothie each day. It almost always depends on the detox, of course; if you're still eating a full diet, your hunger pangs may be coming from another source.
If you're eating less, you're going to be hungrier. That's just how biology works. You're used to getting X number of calories, and if you're not getting that much, you're going to be hungry.
You can fight this off to a certain extent by drinking more water, or something low-calorie like a broth, to give your stomach something to digest and occupy it. A lot of people can mix up hunger and thirst as well. As it turns out, drinking more water is generally going to be a good idea pretty much no matter what your situation is. Exercising, detoxing, cleansing, hiking, watching TV: drink more water.
Detoxes Bring Cravings to the Forefront
The other reason hunger pangs are seemingly more intense or more frequent when you're detoxing is because it's generally a kind of withdrawal. It's a craving, not just for food, but for the specific kinds of foods you're cutting out.
For example, during a sugar detox, you might be eating a normal number of calories in non-sugary foods, but you can still feel these hunger pangs and cravings. The primary cause of these is the cravings for the sugar you're addicted to and that your body is used to getting. Your body wants it, and you have to fight it. The hunger pangs are more cravings than actual hunger.
This is also why, once you've stuck with the detox for a few days or a week or so, you'll notice those hunger pangs dropping off. You're breaking and shaking the addiction, rather than feeding it, and your cravings are subsiding. That's the overall goal of the detox.
If you successfully detox from sugar, for example, then you'll start to notice how sweet everything tastes. Often, when you no longer have cravings, sugary foods won't even taste as good any more. It's an added incentive to keep you from eating too much sugar. If you're detoxing from other ingredients, you may see similar effects, though you might not have as much addictive craving.
Detoxes Include Laxatives and Diuretics
Hunger pangs are not truly related to hunger. Rather, they're a contraction of the stomach when it's empty. You might have consumed more than enough calories to keep you going for the day, but if they were primarily liquid or have already passed beyond your stomach, it can leave the stomach empty. Then you'll get these "hunger" pangs even though your body does not need more nutrients to keep running.
Essentially, your body has become accustomed to a certain level of "fullness", which includes having something actively being digested in the stomach. If your stomach is left empty, even if you're not hungry, your body sends the signal that it needs more food.
Detoxes, especially those fueled with supplements, often include ingredients that have laxative and diuretic effects. In other words, they make you urinate and defecate more frequently. This is used as a sign that your body is purging toxins, and you know what? That's technically true. It's not doing it any better, necessarily, than it normally does. It's just doing it more urgently and more frequently because you're taking drugs that make it do so.
A side effect of purging waste material out of your system is that everything moves into the space that was vacated. Think of a water cooler; when you get water out of it, the rest of the water moves down, leaving open air at the top. In this metaphor, the "top" that has nothing in it is your stomach. And, as mentioned, when your stomach is empty, you feel hunger pangs, regardless of your need to eat.
The best way to deal with this is to spread out what you're eating throughout the day, rather than concentrating it in a few large meals. When you're detoxing, for example, you might make three small smoothies instead of one larger one, and have one every couple of hours, instead. As long as there's always something – even if it's not all that much – in your stomach, you'll quell those hunger pangs.
You're Not Getting As Much Fiber
Fiber is a huge component of a lot of low-carb diets, for two reasons. One reason is that it's food for the gut bacteria that helps keep you healthy; a prebiotic. The other reason is that it's very hard to digest in the stomach, with simple exposure to stomach acid. That means it lingers for a much longer time than other kinds of foods, like fats and proteins. It progresses through your entire digestive system very slowly, providing more nutrients and more fuel overall.
The slowness is the key here. Fiber lingers, keeping you feeling full longer. This suppresses hunger pangs and appetite and helps you stick with your diet.
You can achieve a similar effect with a more balanced diet. High in fiber is good, of course, but you can also eat lean proteins, whole grains, foods with high water content, and vegetables. Then again, it all depends on the kind of detox you're doing.
You're Not Really Hungry
Another side effect of cleansing, detoxing, and dieting, is revealing just how much of your eating habits are from hunger, and how much are from other sources. We already mentioned cravings, but there are other reasons you might feel hungry without actually being hungry.
Foremost among them is a sort of "emotional hunger". It's not the emotional hunger that psychologists talk about, though. It's essentially your habit of eating, and the disruption of that habit. You're used to eating a particular amount of food, and your brain won't feel quite right about it without eating a similar amount of food. Even if you've given your body enough energy to thrive, it wants more, because you're used to eating more.
Another possible reason is simple boredom. Your mind is bored with what you're doing, and you're used to giving it sensation to work with when that sensation comes in the form of giving it flavor to taste and the act of eating to pursue. You might not think you get a lot of entertainment out of eating, and you don't, but it helps occupy a sub-section of your brain to keep you less bored. Think popcorn at a movie; you don't need it to enjoy the film, but your mind might wander if you don't have something to occupy your hands.
You're Taking a Stimulant
Detoxing generally includes supplements of some kind. Often it's a simple multivitamin and nutritional supplement to help keep you going on a low-calorie diet detox. Other times, it might include something like caffeine, or a harsher stimulant. These boost your metabolism by a bit, and more importantly, they stimulate your body converting stored fat into energy. This, especially during a detox, can leave you with excess energy. 
When your body is consuming energy, it naturally wants to replace the energy it consumes. It does this even if you're consuming from a surplus (stored fat) and not from what you're actively eating. This can lead to more psychological cravings pushing you to want to eat more when you don't need to eat quite yet.
Fighting the Hunger Pangs While Detoxing
If you're interested in trying a detox, and you want to fight off the hunger without relapsing in the middle of your cleanse, here are some tips you can follow.
Drink more water. Probably the number one thing you can do when you're detoxing – or even just for health in general – is to drink more water. You'll find very frequently that you're not hungry, but you're actually thirsty, and your body isn't very good at telling you the difference between them. Keeping a bottle of cold water on hand helps satiate those cravings whenever they come up. It's always a good idea to drink more water – in fact, it's almost impossible to drink too much. You'd have to drink several gallons in a matter of an hour or two to reach that point.
Make sure you're actually drinking water, too, not other beverages. Coffee and tea can be good for you in some ways, but they both have caffeine in them, and their nutrients might make you feel hungrier. It's also possible they won't hydrate you all that much. If you absolutely must drink something other than plain water, try a sports drink with electrolytes.
Eat filling foods. Most detoxes don't give you a strict meal plan. Instead, they just limit your calories or tell you to cut out certain ingredients, like sugar and corn syrup. When you're planning your actual meals, pack them full of the most filling foods you can get.
Foods that are good for this include foods that are high in protein, high in fiber, and low in energy density. You can view a list here. In general, you're going to be looking for things like lean meat, vegetables, eggs, fish, and cheese.
Spread out meals throughout the day. If you're stacking up your meals in concentrated mealtimes, you're going to leave yourself hungry with nothing to eat during the downtime. It can often be a better idea to eat several smaller meals throughout the day, more like intermittent snacking than meals. This spreads out your calories and keeps your digestive system full, so there's always something in your stomach.
This doesn't work for everyone. Some people find that it simply leaves them hungry even when they eat, and it makes it even harder for them to stick to their dietary restrictions. Be sure to test it and see if it works for you before banking on it.
Focus on making your own food. One of the biggest problems with store-bought food is all of the sugar and sodium added to basically everything. Sugar is what you're (probably) trying to detox from, and sodium is used in a preservative and has a whole array of negative effects on the body. When you make your own food from whole ingredients, you can better control what you're eating. This makes the detox easier, and it helps reduce cravings for those ingredients.
Get more sleep. When you're asleep, you're not hungry. Also, sleep helps your body process, heal, and recover from the stress it endures during the day. Sleep basically shuts down a lot of your digestive system and allows you to go into "stasis" over the evening, so if you get more sleep, you extend this time of stasis. You'll only start to get hungry if you sleep much longer than normal, or once you wake up and start moving around. We also recommend starting your day with a glass of water. In fact, if you can leave some water by your bedside, drink a glass before you even get up and out of bed. It's a great way to wake up.
Do some exercise. Exercising focuses your body entirely around physical activity, and while you might feel hungry when you're done, you won't feel as hungry when you're working out. You can balance exercise, sleep, and detoxing to help lose weight and cut cravings at the same time.
Overall, it's not too difficult to control hunger pangs; you just need to learn to recognize which hunger pains are actual hunger, which are cravings, and which are your old habits.
